PlumbMate

The standard UK domestic mains supply voltage; homes should not be supplied at more than 230 V.

A bend changing the tube direction by forty-five degrees.

The bonding clamp should be fitted as close as possible to where the pipe enters the property and within 600 mm of the gas/water meter.

A right-angle bend changing the tube direction by ninety degrees.

A plastic that, of the common plumbing plastics, degrades the most when exposed to UV (sunlight).

Alternating current where direction changes repeatedly.

Advisory, Conciliation and Arbitration Service — handles employment disputes, giving free impartial advice and mediating between employer and employee.

Rate of change of velocity, measured in metres per second squared m/s².

The way someone pronounces words, often shaped by where they are from.

Pre-use checks on access equipment: visual inspection, valid tag, fit for purpose and set on secure level ground.

A fitting such as an access bend or a screw-on access cap built into the stack or branch pipework to give access for inspecting and clearing blockages.

A company record where workplace accidents and injuries are logged with the required details.

An injury that happens straight away from a single event, such as a cut or a sprain.

The sticking of water to other surfaces, such as leaves or a car windscreen.

A spanner with a movable jaw for tightening compression joints and nuts; set the adjustor tight so the jaw does not slip.

Passing air through water during treatment to improve taste and remove dissolved gases.

Lets air into the pipework to prevent siphonage, without venting foul air to atmosphere — used on a stub stack instead of an open vent.

The trapped air in a single feed indirect cylinder that keeps the primary (heating) and secondary (hot) water separate; if lost, discoloured water appears at the taps.

Vertical gap between tap outlet and spill‑over level.

Trapped air in a pipe that blocks or reduces flow, common on low-pressure systems.

A manual or automatic valve fitted at high points to release trapped air and prevent air locks.

The amount of air a gas needs to burn completely and safely.

A fitting that removes air from circulating system water to reduce corrosion and noise.

Soundness test for sanitary pipework: pressurise to 38 mm water gauge with a manometer; no pressure drop permitted; hold at least 3 minutes. Smoke testing must NOT be used on plastic pipework.

The kit used to soundness-test sanitary pipework — drain plugs to seal the open ends, a test nipple and rubber hose, hand bellows to add air, a Y-piece and a manometer to read pressure.

A mixture of metals (e.g., brass = copper + zinc).

Brown asbestos — a recognised type of asbestos.

The unit of electric current.

Heat-treating copper to soften it for bending; R220 is pre-annealed (soft), and R250 can be annealed to bend more easily with a spring.

A cylindrical heat exchanger with a hollow centre used in place of a coil in some double feed indirect cylinders.

The less stable (more reactive) metal in electrolytic corrosion, which is corroded away.

Building up a protective oxide layer on a metal (usually aluminium) by electrolysis to resist corrosion.

A type of coal burnt as a solid fuel.

A valve (often a check valve) fitted on shared pipework in a semi-gravity system so water only circulates when the pump runs.

A trap with an air inlet that prevents the seal being siphoned out.

A liquid (normally ethylene glycol) added to water to lower its freezing point, used in systems such as solar thermal circuits.

The Association of Plumbing and Heating Contractors — the plumbing trade association, supporting contractors with subsidised training, articles and professional advice.

Structured training combining on‑the‑job learning with classroom study.

Practical guidance with special legal status: follow it and you are doing enough to comply with the law.

A permeable rock layer that stores groundwater.

A method of resolving disputes outside the courts.

The designer who produces the building drawings and oversees the design intent.

The amount of space inside the boundary of a 2-dimensional shape, measured in metres squared (m²); for a rectangle, length × width.

Cable with a steel "armour" layer protecting the wires within; used by the electricity supplier and as the earth path in a TN-S system.

A well where water rises naturally under pressure.

A bonded asbestos material (e.g. old flue/roof sheets) that is dangerous if cut or broken, releasing fibres.

Serious long-term lung diseases caused by inhaling asbestos fibres, including asbestosis and mesothelioma.

A bidet with a spray that rises from below — a high backflow risk that must not be fed directly from the mains.

Corrosion caused by air and moisture attacking a metal surface over time.

The pressure exerted by the weight of air; just over 1 bar at sea level, decreasing with height as there are fewer air molecules.

The smallest part of an element, made up of protons, neutrons and electrons.

An air gap of the type found between a WC pan and cistern, giving backflow protection up to fluid category 5.

An air gap found on basins and baths giving protection to fluid category 3; sized 20mm for a 15mm (1/2") inlet or 25mm for a 22mm (3/4") inlet.

An air gap found on over-the-rim bidets and kitchen sinks protecting up to category 5; at least 20mm and twice the diameter of the inlet.

A valve that opens to maintain flow when radiator/zone valves close, protecting the pump and boiler.

An open fire with pipes through the flue area that heat water for the cylinder and some radiators.

Reverse flow of contaminated water into clean supply.

A fitting that stops used or contaminated water flowing back into the supply.

Heating the whole property to a lower temperature than full heating

Backflow caused when pressure in part of the system is higher than the mains (from pumps or heat expansion), forcing water backwards.

Negative pressure drawing contaminated water backwards.

A supply where the hot and cold are at similar pressures (both high or both low), required to feed blending valves and thermostatic showers.

Adjusting the lockshield valves so each radiator gets the right share of flow — closed more on radiators near the pump, opened on those furthest away.

A small screwdriver-operated isolating valve usable as a service valve on the high-pressure inlet before a float valve.

A practical unit of pressure roughly equal to atmospheric pressure (100,000 Pa).

Plastic heating pipe with an oxygen barrier layer to stop oxygen entering and corroding the system.

The lowest branch connection sits ≥450 mm above the drain invert in buildings up to 3 storeys, rising to ≥750 mm in 4–5 storeys. In 6–10 storeys no branch connects on the ground floor. A long radius bend (≥200 mm radius) eases the vertical-to-horizontal transition and reduces back-pressure.

Wash basins named by how they are fitted: countertop, semi-countertop, under-countertop, wall-hung and pedestal.

A combined bath tap and shower mixer that blends hot and cold to feed the shower.

Cutting the sides of an excavation back to a safe angle so they are less likely to collapse.

A cordless rechargeable drill used for drilling and driving on site.

The buried pipework carrying foul and/or surface water away to the sewer or treatment.

Record of installation and servicing for boilers and cylinders.

Angled cylinder connection for tight spaces.

Where a pipe narrows the water speeds up and its pressure falls; where it widens again the water slows and the pressure recovers.

A mixer tap in which the hot and cold do not mix until they leave the spout, removing the need for backflow protection.

A tap fixed to a wall via a backplate; typically used as an outside tap or over a cleaner's sink.

A washing appliance made as over-the-rim or ascending-spray; because of the back-siphonage risk, ascending-spray and hose types must not connect to the cold mains, or be fed through a combi or unvented supply, without an adequate air gap (AUK3).

A solid fuel boiler that burns organic material such as wood pellets

A valve fitted at a high spot to release trapped air and clear an air lock.

A valve that mixes cold water into the hot to limit outlet temperature and reduce scalding; the only place regulations require one in a new domestic property is the bath (max 48C).

Tools used to clear drainage blockages — a force cup (plunger), gully grab, drain rods and a drain auger.

A gas torch used to heat fittings when soldering copper.

Corrosion of new copper pipework caused by water stagnation, giving drawn water a cloudy blue appearance.

A radiator connected at the bottom at opposite ends — the most common arrangement.

Repeated short bursts of firing and switching off as a boiler reaches and loses temperature, which wastes fuel.

Control wiring that shuts the boiler and pump down when no zone is calling for heat (all thermostats/valves satisfied) — a Building Regs Part L energy-efficiency requirement. [Verify wording — not defined in source.]

Water changing state from a liquid to a gas (steam), which occurs at 100°C.

A pumped (booster set) system used where mains pressure or flow is insufficient — tall buildings or weak mains.

A deep drilled hole accessing underground water.

A connection point on a soil stack for a branch discharge pipe — a boss is used on a new stack, while a strap-on (patch) boss is clamped on to connect into an existing stack.

A compact trap where water seals in a removable 'bottle', used where space is tight.

A waste pipe that carries the discharge from an appliance to the main soil stack, coming off the stack like branches off a tree.

An alloy of copper and zinc that is stronger than copper while keeping its corrosion resistance.

A brass ring with a backplate that holds pipe a set distance off the surface; strong enough for copper or steel.

A strong brass bracket clip that holds pipe off the surface; strong enough for copper or steel pipework.

The trade that lays bricks and blocks to build walls.

Published standards setting agreed ways of doing things or required quality.

An alloy of copper and tin that is stronger than copper while keeping its corrosion resistance.

The main British Standard for open vented central heating systems.

The British Standard giving the activity-space dimensions needed around sanitary appliances such as WCs, basins, baths and bidets.

The British Standard (the Wiring Regulations) covering safe electrical design and installation; not law itself but recognised good practice.

The British Standard covering workmanship on building sites; Part 15 covers hot and cold water services.

UK guidance complementing BS EN 806 on designing, installing, testing and maintaining water services.

The standard for gravity drainage systems inside buildings.

The European Standard for the manufacture and rating of radiators.

The standard for the design and installation of water supply systems inside buildings (parts 1–5).

The standard covering float valves in four parts; Parts 2 and 3 work the same internally, Part 1 is the original bottom-outlet type, and Part 4 (Torbeck/equilibrium) is designed for mains pressure.

A radiator with flow and return into the bottom at the same end, using single entry radiator valves.

The official who checks that work complies with the Building Regulations.

Statutory rules for building work in England & Wales; plumbing must comply (e.g. limits on notching/drilling joists). (Spans several units.)

The Building Regulations covering drainage and waste disposal.

The explanatory document setting out how installers can meet Part L of the Building Regulations.

An engineer who designs a building's services, such as a large central heating, water or electrical system on a major project.

The engineer who designs services such as heating, water, ventilation and electrics.

A Building Control Officer with specialist plumbing, heating, or electrical knowledge.

A liquefied petroleum gas (LPG) used for portable heating; heavier than air and slow to vaporise when cold.

The person who purchases materials and equipment for the project.

A control layout for gravity hot water with pumped heating.

The covering around conductors that prevents contact and current leakage; cables normally have insulation on each wire and around the whole cable.

Where hidden cables may run in walls: within 150 mm of the top of a wall, within 150 mm of a corner, or directly in line (vertical/horizontal) with an accessory. Don't drill into a zone.

A dissolved compound that makes water temporarily hard; the type of hardness that causes limescale when heated past 65°C.

A dissolved compound that makes water permanently hard; this type of hardness does not cause limescale.

The heat energy released when fuel is burned.

The amount a container can hold, measured in litres (l).

The ability of water to be drawn into narrow spaces against gravity, caused by adhesion to the surrounding material.

Used in pipe-freezing kits — it expands rapidly leaving the canister, dropping temperature enough to freeze a plug so work can be done without draining. Dissolved CO₂ also makes soft water acidic.

Measured in flue gas analysis alongside CO and oxygen; the CO/CO₂ ratio indicates combustion quality.

A toxic product of incomplete combustion. Measured in flue gas analysis — a high CO reading or poor CO/CO₂ ratio indicates incomplete combustion and must be investigated.

A sealed fuse with a wire element inside a ceramic body that blows to break an overloaded circuit.

The more stable (less reactive) metal in electrolytic corrosion, which takes electrons from the anode.

Construction (Design and Management) Regulations — govern health and safety on construction projects; the principal/main contractor is responsible for site welfare facilities.

A ladder used to access a loft; if none is fitted, use an extension or pole ladder.

Add 273 to convert °C → K. Water freezes 0°C/273 K, boils 100°C/373 K; absolute zero = −273°C/0 K.

A prefix meaning a hundredth; e.g. 1 cm = one 100th of a metre.

One source serves the whole property; can struggle to reach remote outlets (dead leg/cooling).

A measurement taken from the centre of one pipe to the centre of the next, keeping runs evenly spaced and parallel.

The material most sanitary ware such as basins and toilets is made from.

The cartridge in a ceramic disc tap that is replaced to cure a tap passing water.

A tap that seals using two ceramic discs rather than a washer, needing only a quarter turn.

To take the sharp, square edge off a pipe end at a shallow angle.

A MEWP with an articulated/telescopic boom that reaches up and over obstacles.

The Central Heating System Specifications — an Energy Saving Trust document describing how to install an efficient heating system.

A flooring board of compressed wood chips, often tongue-and-groove and moisture-resistant.

A sharp-edged tool struck or pushed to cut or chase out timber, brick or masonry.

Adding chlorine to water to kill bacteria as part of treatment.

An injury that builds up slowly over time, such as from repeated poor manual handling.

White asbestos — a recognised type of asbestos.

Chartered Institute of Plumbing and Heating Engineering.

A powered saw with a rotating blade for straight cuts in timber and boards.

The pump that circulates water around the heating system.

The distance all the way around the outside of a circle.

The Construction Industry Training Board, which supports training and skills across construction, including the CSCS scheme.

The client's on-site representative who checks that work meets the drawings and standards.

The most important person in a project — they agree the look and materials with the architect and pay for the work to be carried out.

Maximum spacing between pipe supports (horizontal / vertical): Steel 15mm 1.8/2.4 m, 20mm 2.4/3.0 m · Copper 15mm 1.2/1.8 m, 22mm 1.8/2.4 m, 28mm 1.8/2.4 m · Plastic pressure 15mm 0.3/0.5 m, 22mm 0.5/0.8 m · Waste 32 & 40mm 0.5/1.2 m · Soil 110mm 1.0/2.0 m. Vertical can be wider than horizontal; stiffer/larger pipe allows wider spacing; plastic needs the closest support.

Bringing the cold feed and open vent into the system within 150mm of each other to help prevent pumping over.

Practical guidance on recommended ways of carrying out work.

The sticking of water molecules to each other, which makes water form rounded droplets.

A leak in the cylinder coil that lets primary heating water mix with the stored hot water, often shown by discoloured water at the taps.

Pipe supplying water from a cold water storage cistern to outlets.

In a gravity hot water system, the pipe from the cistern that fills the hot water cylinder.

A pipe carrying mains water at high pressure to appliances.

A lidded, vented tank that stores cold water to feed outlets in an indirect system.

A radiator made of vertical columns, traditionally cast iron, with a high water content.

A boiler providing instantaneous hot water and central heating from one unit, with no hot store.

A cylinder with an integral cold water cistern on top, combining storage in one unit.

A cold water system described alongside direct and indirect, combining features of both.

A below-ground system carrying foul and rainwater in one pipe.

The burning of a fuel, which needs oxygen, heat and fuel (the fire triangle) to start and continue.

Final checks ensuring the system operates correctly.

Typical site dangers: trailing leads, slippery/uneven surfaces, dust and fumes, manual handling, fire, working at height, faulty equipment and possible asbestos.

Verbal — for simple/informal exchanges; needs speaking and listening. Written — for formal matters and records. Non-verbal/body language — read whether the customer is following. Barriers and fixes: impaired hearing → written notes; non-English speaker → interpreter.

The underground supply pipe from the water main to the boundary stop valve, owned by the supplier.

A pressed-steel panel radiator, often with convector fins, the most common emitter.

The government department that every limited company in Britain must register with, which collects and stores information about them.

The person a public limited company (PLC) must appoint by law to keep the company organised.

Sole trader — one person owns and runs it. Partnership — two or more share profits and liabilities. Limited company (Ltd) — owners have limited liability for debts. PLC — public limited company that can sell shares to the public.

To do as a rule, standard or instruction requires.

A mechanical joint sealed by an olive squeezed between the nut and body. Non-manipulative uses a standard olive; manipulative flares the pipe end (often gas service) and cannot be reused. There are also different compression fittings for 32mm and 40mm plastic wate pipes and again for Low Carbon Steel.

A squashing force, where two forces push directly towards each other.

A material's resistance to compressive force, where two forces push directly towards each other.

A thermostatic shower valve hidden behind the wall surface, fed with a balanced supply.

The slightly acidic liquid formed when water vapour in the flue gases cools and condenses, as in a condensing boiler; it drains away through the condensate pipe.

Water vapour cooling to form droplets or clouds.

The pipe that carries away the water produced when flue gases condense in a condensing boiler.

A boiler that extracts extra heat from the flue gases so the water vapour condenses; it needs a condense pipe to remove the water.

Heat transfer through solids by direct contact.

Rigid or flexible tube that contains and protects cables.

An enclosed or partially enclosed space with limited access and a risk of serious injury.

Regulations requiring confined-space work to be avoided where possible, or carried out under a safe system of work.

Handling disagreements on site — between customers and operatives, co-workers, or supervisors and operatives — by staying calm, communicating clearly and involving a supervisor where needed.

Scale drawings showing how to build, including the site/location plan, floor plan, section, elevation, component drawing and schematic.

The person managing the day-to-day running of the construction site.

The enclosure containing the main switch and protective devices that distributes circuits around a dwelling.

A test that checks earth/CPC conductors are unbroken by measuring resistance, which should read low ohms.

A formal written agreement setting out an employee's terms and conditions of employment.

The person overseeing one or more contracts and the site teams delivering them.

Regulations setting out how work that may disturb asbestos must be assessed and controlled.

Regulations protecting workers' hearing; hearing protection is available on request above 80 dB and must be provided above 85 dB.

Heat transfer through liquids or gases by circulation.

Metal fins welded to a radiator panel to increase its surface area and heat output.

An emitter that heats mainly by warming air passing over fins rather than by radiation.

A boiler for open vented heating that circulates water through separate heating and hot water circuits, needing all control components fitted separately.

R220 soft copper — coils, pre-annealed for hand bending. R250 half-hard — straight lengths, the most common. R290 hard — lengths, not for bending.

A copper clip that holds pipe close against the surface; mainly for copper, with similar styles for other materials.

A bench/floor-standing bender for accurate bends in 15–28 mm copper using interchangeable formers.

Plumbing tube supplied soft (R220), half-hard (R250) and hard (R290); jointed by solder, compression or press-fit.

The breakdown of a metal caused by a chemical or electrochemical reaction with its surroundings, such as rusting.

A chemical added to system water to slow corrosion and scale inside pipes and components.

A material's ability to resist corrosion; copper and stainless steel are highly corrosion resistant.

Acids or alkalis that can burn or destroy living tissue and metals.

Control of Substances Hazardous to Health.

The unit of electrical charge; one amp is a flow of one coulomb per second (about 6.241x10^18 electrons).

A screw with a tapered head that sits flush with or below the surface.

A fitting that makes a straight connection between two pieces of pipe.

Circuit Protective Conductor.

Continuing Professional Development to maintain and update skills.

A board that spreads a worker's weight across roof joists/rafters to prevent falls through the surface.

Forming a permanent joint by compressing a press-fit fitting onto the pipe with a crimping (pressing) tool — common on copper and multilayer pipe.

Compressing a metal terminal or connector onto a stripped cable end with a crimping tool to make a secure connection without solder.

A tool that compresses a connector onto a conductor to make a secure joint.

Blue asbestos — a recognised type of asbestos.

An incorrect connection that could let non-wholesome water mix with the wholesome supply.

Pressure-fluctuation trap seal loss that can occur when two branch pipes discharge into the stack directly opposite each other; prevented by an exclusion zone, a 90° connection, or a soil manifold.

A card proving you are trained and have adequate safety knowledge for your role; needed, with the relevant minimum trade qualification, to work on most building sites.

The amount of electricity flowing round a circuit, measured in amps (symbol I).

A customer's right to cancel a signed contract, usually up to a week after signing unless work has started, and to claim for poor or overlong work.

A policy a company produces setting out expectations — good timekeeping, clean appearance, open communication, good workmanship and tidying up — to keep customers happy and protect its reputation.

A thermostat strapped to the cylinder that controls the stored water temperature.

A COSHH classification for substances that can harm the environment now or in future, such as heavy metals like lead or mercury.

The law governing how personal information must be handled and kept secure.

Direct Current — flows in one direction.

The government department responsible for writing the Building Regulations (since renamed MHCLG).

A length of pipe with no return. If not connected to an outlet it can allow stagnation of water.

Taking a system out of use, either temporarily (drained, capped) or permanently (disconnected).

The trade that paints and decorates surfaces.

A high-capacity gutter profile used where a large roof area or heavy rainfall means more water must be carried away; one of the four main shapes alongside ogee, half-round and square.

The government department responsible for environmental protection, food standards and rural affairs, which created WRAS and OFWAT.

Passing the authority and responsibility for a task from one person to another, such as supervisor to operative.

Document listing materials delivered to site.

The difference between a radiator's mean water temperature (average of flow and return) and the room temperature — used in heat-output sizing.

The amount of mass contained within a set volume; calculated as mass divided by volume.

Units of measurement made by combining the base SI units, such as metres per second or newtons.

A painful allergic skin reaction from repeated contact with substances such as flux, cement, plaster, soaps or water.

Removing limescale from cylinders and pipework.

The pressure a sealed system is set to run at, which may need topping up after bleeding radiators.

To move away from the agreed plan, method or standard.

The temperature at which water vapour in a gas cools enough to turn back into liquid droplets.

Corrosion where zinc is removed from brass fittings.

A regional or social form of a language, with its own words, pronunciation and grammar.

A straight line passing through the centre of a circle from one side to the other; twice the radius.

The washer inside a Part 2 or 3 float valve; a worn or split diaphragm makes the valve flow continuously.

A fitting used between galvanised LCS and copper that reduces electrolytic corrosion between the two metals.

Every outlet is supplied straight from the mains; no storage cistern feeds the outlets.

The domestic hot water is heated DIRECTLY by the heat source, with no heat exchanger between — a direct cylinder (boiler primary water flows through it), a combi (heated on demand, no cylinder), or a cylinder with an immersion heater.

The pipe from a temperature/pressure relief valve that falls continuously to discharge to a safe place outside.

Treating someone less favourably because they are different — directly (because of a protected characteristic) or indirectly (a general rule that disadvantages a group); related conduct includes harassment and victimisation.

Cleaning the system of debris and flux residues by flushing; domestic systems use wholesome water, commercial systems may use chlorine-based products.

A backflow device with two check valves in series, used e.g. on an outside tap.

An indirect cylinder where the hot water is kept separate from the heating water by a coil, fed by a separate CWSC and a separate F&E cistern.

Two layers of insulating material between live parts and the user, making an appliance or cable safer.

Switch that isolates both Live and Neutral.

The vertical pipe carrying rainwater from the gutter to the drain or soakaway.

Screw-together rods pushed into a drain to clear a blockage.

An inflatable or screw plug used to seal a pipe for an air (soundness) test.

A valve fitted at low points to drain water from the system.

Combined — one pipe carries both foul and surface water. Separate — foul water and surface water in separate pipes (surface water to a soakaway, stream or river). Two-pipe — soil and waste on separate stacks (older).

Procedure to empty a system: isolate the supply, then drain all pipework from the lowest point.

The inspectorate that checks drinking water quality, verifying the water companies' test results and requiring improvements if standards are not met.

A heating system that uses electrical elements in the heat emitter to heat the room, rather than water.

Toilet with reduced and full flush options to save water.

A material that can be drawn into wire (e.g., copper).

Forming or using a channel/enclosure to run pipework through the structure.

The people with health & safety duties on site — employers, employees, contractors and visitors.

The legal and moral duty to take reasonable care so that your work does not harm others.

Pressure when water is flowing.

An on-the-spot assessment of the hazards and controls for a situation as it is found, made by the worker before starting.

The clamp used to fix an earth bond to a pipe; it carries the label "Safety Electrical Connection - Do Not Remove".

A check that the earth path is unbroken and of low enough resistance to protect against faults.

Current flowing to earth due to a fault.

TT — earth via an earth electrode at the property. TN-S — separate earth via the cable sheath. TN-C-S (PME) — combined neutral and earth from the supplier, separated at the property.

The Electrical Contractors Association — the trade association working on behalf of the electrical industry, offering members subsidised training.

Guard rails and toe boards fitted to stop people or materials falling from an edge.

Adapting how you communicate so everyone can understand — for people with physical disabilities, learning difficulties, or language differences such as dialects, accents and English as a second language (e.g. backing up verbal with written communication).

Poor communication causes mistakes, delays, wasted materials, conflict and unhappy customers.

The HSE publication listing Workplace Exposure Limits (WELs) — the maximum concentrations of hazardous substances permitted in workplace air.

A fitting that changes the pipe direction; types include knuckle 90° (tight), swept 90° (long radius), 45° and street (one male end).

The supplier's meter that records the electrical energy used in the dwelling.

Steps for an electric shock: isolate/remove the supply safely, call emergency services, apply CPR if trained and treat burns.

A powered bending machine for quick, repeatable bends where many or larger bends are needed.

The earth bonding on metal pipework, cylinders and baths, checked as a safety step during maintenance.

A material that allows electrons to flow easily (e.g., copper).

Site electrical risks: faulty/damaged equipment, exposed conductors, damaged insulation, worn or trailing cables and buried/hidden cables.

A material that resists electron flow (e.g., plastic).

A device that switches a circuit on/off automatically at set times (e.g. heating or immersion).

The trade that installs and tests electrical systems.

Laws requiring safe working practices with electrical systems and equipment.

The device that measures the amount of electricity used in the property.

A liquid that lets electric current pass through it; water conducts more readily the more dissolved salts or minerals it holds.

Corrosion when three conditions coincide: two dissimilar metals, water/electrolyte, and electrical continuity. The less noble metal (e.g. iron) corrodes preferentially.

A list ranking metals from most cathodic to most anodic; the further apart two metals are, the greater the corrosion reaction between them.

A tiny charged particle whose flow through a material is electricity; materials with many free electrons are good conductors.

Reactive work carried out to fix an unexpected fault or breakdown, such as a burst pipe or dripping tap.

Legislation giving workers paid holiday leave and setting out maternity and paternity leave requirements.

A body an employee can refer an employment dispute to, such as one about dismissal or redundancy.

A baked protective/decorative coating applied to metal to resist corrosion.

Copper fitting requiring added solder during heating.

A company policy setting out how it limits its impact on the environment, such as waste, recycling and water-use procedures.

The principle and law that people must not be discriminated against unfairly.

The law that brought the earlier anti-discrimination laws together, making it illegal to discriminate on grounds of race, gender, religion, sexual orientation, age or disability.

When all forces and moments are balanced.

Connecting exposed metalwork together so it all sits at the same electrical potential, removing shock risk; not required for plastic pipework.

Corrosion caused by the pressure and speed of water creating turbulence at fittings such as elbows and tees, mainly in pumped hot water systems.

Wrong or incorrect.

An approximate price for work that may change, unlike a fixed quotation.

The person who prices the work to produce tenders and quotations.

Liquid water turning into vapour.

Keeping trenches safe: safe access, support systems, warning signs, barriers and keeping vehicles back from the edge.

The deliberate gap left so plastic pipework and guttering can expand and contract — for example pulling a pushfit pipe back 10mm after seating it, or fitting gutter only to the 'insert to here' mark.

Ticking noises from pipework as it heats and cools, cured by fitting felt or insulation so the pipe can move without sticking.

Water expands as it freezes and as it is heated, which systems must allow for.

The pipe from an expansion relief valve, run at a fall to discharge in a visible and safe position; minimum 15mm on a small boiler.

A safety valve on sealed systems (unvented cylinders, combi boilers) that releases water if pressure or temperature rises past a safe level. Runs at a fall to discharge in a visible and safe position; minimum 15mm on a small boiler.

A vessel with a pressurised air cushion that absorbs the expansion of water as it heats, on sealed heating systems and unvented hot water cylinders.

A COSHH classification for substances that can explode, shown by an exploding-bomb symbol.

An extendable ladder used to reach work areas such as roofs or scaffolds, or for short work only.

A spring slid over the outside of the tube to support a bend made close to the pipe end.

The homeowner's pipe (usually blue 25mm MDPE) running from the property boundary into the house, buried between 750mm and 1350mm deep.

Voltages of 50 V AC or less (e.g. 12 V, 24 V) used to reduce shock risk in certain locations.

The slope given to a drainage pipe so waste flows at self-cleansing velocity; branch waste pipes are generally laid between 18 and 90mm per metre (18–45mm per metre for 32mm pipe).

A flue using a fan to ensure enough air for efficient combustion in a room sealed appliance.

A heat emitter that uses a fan to accelerate air movement over a heating coil, boosting heat output into the room.

A board fixed to the rafters along the edge of the roof, to which fascia gutter brackets and fittings are screwed.

A small cistern that fills an open-vented heating system and takes up the expansion of heated water.

A metal containing iron (e.g., steel, cast iron).

Removing particles from water by passing it through a filter medium during treatment.

Fires by what's burning: A solids (wood, paper, textiles); B flammable liquids (petrol, oils); C flammable gases (LPG, propane); D flammable metals (magnesium, titanium); E electrical.

A material similar to ceramic but heavier and more robust, used for shower trays and kitchen sinks.

Matched to the fire class: Water (red) → Class A only (never electrical); Foam (cream) → A and B; CO₂ (black) → electrical and liquid fires; Powder (blue) → multi-purpose (A, B, C). Use PASS: Pull, Aim, Squeeze, Sweep.

The three things a fire needs — fuel, oxygen and ignition (heat); remove one to put it out.

Regulations requiring employers to provide adequate first-aid equipment, facilities and trained people.

The preparatory and installation work done before fitting the boiler and radiators, such as running pipework.

A proprietary range of wall plugs and frame fixings for securing components to different surfaces.

A tube-and-fitting or system scaffold erected by trained scaffolders for longer-duration work at height.

Common surfaces — wood, block, tile, plasterboard, brick — each needing a suitable fixing.

Match the fixing to the wall: masonry → wall plug (drilled with a hammer drill); hollow wall/plasterboard → cavity (spring) toggle / hollow-wall anchor / toggle bolt, which springs open behind the board to spread the load. Always use a pipe & cable detector before drilling.

Substances that ignite easily; stored away from ignition sources and shown by the flame hazard symbol.

An appliance with a large flat base (a bath or shower tray) whose last water trickles slowly into the trap and recharges the seal, which is why it can use a reduced 50mm trap seal (38mm on a gully).

Flexible cable used to connect appliances; chosen for current and, where hot, heat-resistant flex is used.

A rubber coupling used to join pipes of different materials or diameters, such as clay or cast iron to plastic; it must be the correct size to fit around the outside of both pipes.

A valve in a cistern that shuts off the inflow when the float rises to the set water level.

Volume of water passing a point per second. This can be measured in litres per second (l/s) or metres cubed per second m³/s

A mechanical switch that turns a shower pump on or off in response to water flow; a common fault if the pump fails to start or stop.

A duct or pipe that carries exhaust gases from a boiler or appliance to the outside.

Any substance whose molecules move freely past one another and take the shape of their container — both water and air are fluids.

Backflow risk classification: FC1 wholesome mains water; FC2 aesthetic change (taste/odour/temperature); FC3 slight health hazard (e.g. heating water); FC4 significant hazard (e.g. pesticides); FC5 serious hazard (e.g. human/butchery waste). Protection: single check valve FC2; double check valve FC3; RPZ valve FC4; AUK2 air gap FC3; AUK3 air gap FC5.

Running wholesome water through a system after work to clear debris before use.

The mechanism inside a WC cistern that releases the flush — a flap valve, a drop valve or a siphon.

A paste/liquid that cleans metal for soldering; some types are corrosive or irritant and need careful handling.

A pipe insulation with a foil outer layer, one of the insulation types used on central heating pipework.

A push or pull measured in Newtons.

A non-renewable fuel such as natural gas, coal or oil that releases carbon dioxide when burnt.

Water changing state from a liquid to a solid (ice), which occurs at 0°C and causes a 10% expansion.

The resistance to water flow caused by pipe walls, fittings and bends, which reduces pressure.

Protecting exposed/unheated pipework from freezing with insulation and trace heating (electric heating cable around the pipe). Internal pipework in a heated building doesn't normally need it.

A thermostat that switches the system on to protect pipework from freezing, set to about 5C when sited outside the heated area.

A service valve with an unrestricted bore, fitted either side of a pump to make maintenance easier, or on low pressure hot and cold water systems.

A system that heats the whole property to an agreed comfortable temperature.

A system where a pump circulates both the heating and the hot water cylinder circuits.

Switched connection unit with built-in fuse.

Unvented hot water work is notifiable and must be carried out by a G3-qualified (competent person) installer under Building Regs Part G3. The tundish is fitted vertically within 500 mm of the relief valve; the discharge pipe runs to a safe, visible termination and is at least one size larger than the relief valve outlet.

Banding fixed over the top of insulation to support pipework run under floors.

Coating steel with zinc to protect it from corrosion.

Oxygen black (white shoulder in current standards); acetylene maroon; propane red; nitrogen grey.

Cylinders stored upright, secured, ventilated, away from heat and sources of ignition, and transported safely.

The Gas Safe registered trade that installs and services gas appliances.

The body whose recognised qualification you must hold before carrying out gas work, renewed every 5 years; it replaced CORGI in 2009.

A COSHH classification for gases stored under pressure, such as LPG bottles, shown by a gas-cylinder symbol.

A full-bore isolation valve for low-pressure pipework such as tank-fed supplies.

A portable engine-driven generator providing power where no mains supply is available.

A renewable heat source that draws warmth from the ground to heat water.

An open vented cylinder rated for up to 10 metres of head, the grade most commonly fitted in domestic properties.

Circulation driven by heated water rising and cooler, denser water falling towards the boiler; only usable on solid-fuel systems.

Also known as an open vented hot water system, where water is to the cylinder from a cistern by gravity.

A shower fed by the head of water from a cistern above, giving lower pressure.

Wastewater from baths, basins, and showers.

The fair process a company must have in place for handling employee complaints and disciplinary matters.

Rainwater that has soaked into the ground, as opposed to surface water that flows over the land.

The trade that prepares the ground, foundations and below-ground drainage.

The recommended guidance document that explains how to meet the Water Supply (Water Fittings) Regulations.

An external fitting with a water-sealed trap into which appliances (other than WCs and urinals) can discharge; the waste pipe should finish below the grid but above the water seal.

A copper alloy that is stronger than copper while retaining copper's resistance to corrosion.

A support that holds guttering — the fascia bracket (most common, screwed to the fascia board), rafter brackets (top or side fix, to the rafters) and drive-in brackets (driven into brickwork where the others can't be used).

The slight slope a gutter is laid to so water flows to the running outlet — recommended at least 1mm drop for every 600mm of run (a ratio of 1:600).

A fitting that closes off the end of a gutter run.

A fitting that joins two lengths of gutter and leaves space for thermal expansion; a common cause of a leaking union is the rubber seal being out of place.

Collects roof rainwater to stop water penetrating the structure. Profiles: half-round, ogee, square. Laid to a fall (≈1:600); brackets within 150 mm of joints, outlets and stop ends; a 10 mm gap at unions allows expansion.

The trade that installs heating and ventilating systems.

A fine-toothed saw used to cut metal tube and sections.

A shallow double bend that lifts the pipe partly over a small obstruction.

A common semicircular-profile rainwater gutter.

A striking tool; the claw hammer drives and pulls nails, while a lump (club) hammer drives a bolster or cold chisel into masonry.

A painful, disabling condition of the hands and arms caused by prolonged use of vibrating tools, causing numbness, tingling and loss of grip; controlled by limiting daily tool exposure.

The final commissioning stage: handing over documents and warranties and explaining how the system works to the customer.

The documents and instructions given to the customer when work is completed.

Water containing dissolved calcium and magnesium salts.

A material's resistance to scratching, denting or wear.

Substances that can cause limited health effects if swallowed, inhaled or absorbed, shown by the CLP hazard symbol.

Fall-arrest PPE worn at height, clipped to a secure anchor by a lanyard.

Anything with the potential to cause harm.

The vertical height of water above a point, which creates the pressure at that point.

A written policy required once a company employs 5 or more people. Three sections: statement (commitment/aims), responsibilities (who does what), arrangements (what's done in practice).

A COSHH classification for substances that cause long-term (chronic) illness, such as lead and asbestos.

PPE such as ear defenders worn against noise; provided above 85 dB and available on request above 80 dB.

How well a material lets heat pass through it; copper is a good conductor, plastic a poor one.

Energy measured in Joules that transfers between materials by conduction, convection and radiation.

Coil or plate transferring heat without mixing water.

A radiator (often a towel rail) that lets primary water circulate to dump heat when the zone valve has closed; required on solid-fuel systems.

The heat a room loses through its fabric and ventilation, which the radiator output must match or exceed.

The amount of heat a radiator gives off, measured in watts and listed in the manufacturer's catalogue.

A low-temperature renewable heat source well suited to underfloor heating.

Flexible cable with heatproof insulation, used in warm areas such as from a spur to an immersion heater.

One-pipe: flow & return share a loop, rads cool progressively. Two-pipe: separate flow & return, equal temp to every rad. S-Plan: two 2-port motorised valves. Y-Plan: one 3-port mid-position valve (<150 m²). S-Plan Plus: 3+ 2-port valves (>150 m²/multi-zone). C-Plan: semi-gravity (gravity HW + pumped heating).

The unit of frequency — cycles per second. UK mains AC runs at 50 Hz.

The five levels of hazard control, most to least effective: 1) Elimination, 2) Substitution, 3) Engineering controls, 4) Administrative controls, 5) PPE. Always start at the top; PPE is the last resort.

A cartridge-type fuse designed to work safely at higher currents than a normal cartridge fuse.

A hot water storage cylinder with a large heat exchanger so it reheats the stored water quickly.

By law a worker is entitled to 5.6 weeks of paid leave a year (e.g. 28 days for a five-day week); employers may count public holidays within this.

The pipe from an open vented cylinder delivering hot water at low pressure to the outlets; minimum 15mm, usually 22mm on main runs.

Hot water supplied at mains pressure from an unvented cylinder or combi boiler; minimum size 15mm.

A control required before soldering/brazing in an occupied building — manages the naked-flame fire risk. Check the blowtorch hose and connections first.

Health and Safety Executive.

A Health and Safety Executive inspector who enforces health & safety law on site.

Health & Safety at Work Act — places duties on both parties. Employer: provide safe systems of work, training, PPE, safe equipment, welfare facilities. Employee: take reasonable care for self and others and cooperate with the employer.

A bender using hydraulic pressure to bend LCS; because LCS springs back, bends are overbent by about 5° (e.g. a 45° bend is formed to 50°).

A prefabricated aluminium or steel strut system supporting trench sides, which can be installed without entering the trench.

Pressure test using water to check for leaks. Metal pipework: stabilise 30 minutes, then test 60 minutes; any pressure drop is a fail. Flush with wholesome water.

A trade body for the electrical and engineering industries, involved in standardising the wiring regulations.

The temperature at which a fuel will start to burn.

Electric element used to heat water in a cylinder.

The part of an immersion heater that heats the water; if it fails the whole immersion heater must be replaced.

A legal notice requiring unsafe conditions to be put right within a set time.

In its existing or installed position — already in place.

A solid fuel boiler that heats water circulated to the cylinder and radiators, with controls that cut air to the fire when up to temperature.

A scaffold that stands on its own on at least four legs, not relying on the building for support.

Most outlets are fed from a cold water storage cistern; only the kitchen sink stays on the mains for drinking water.

The domestic hot water is heated INDIRECTLY through a coil or annulus (heat exchanger). Primary heating water passes through the coil and warms the secondary water without the two mixing.

Trap seal loss caused by discharge from another appliance pulling water out of the trap.

A single point water heater design where the control valve is on the inlet and heated water spills over into a combined outlet/vent.

Appliance-specific manufacturer information giving how to install, commission, maintain and fault-find a particular appliance.

Shower that heats water on demand.

Hot water heated on demand as it flows, with no storage vessel.

Hand tools with insulated handles rated for working safely on or near electrical equipment.

Insulated cutters used to cut domestic cable safely.

Confirms cable insulation is sound. Applies 500 V DC; minimum acceptable reading for a 230 V circuit is 1 MΩ. Instrument often called a Megger.

A trap on older foul drains at the connection to the public sewer, to stop sewer gases and vermin entering the drain.

A spring inserted inside soft copper to support the bore so it does not collapse when bent by hand.

Fitted where a plastic pipe passes through a fire-rated wall/floor; in a fire it expands inward as the pipe melts, sealing the opening to stop fire/smoke spread.

The lowest inside surface (bottom of the bore) of a drain or bend, used as the datum when setting the minimum height of the lowest branch connection at the base of the stack.

A document requesting payment for work done or goods supplied.

Substances that cause inflammation or discomfort to skin, eyes, or respiratory system.

A switch that fully disconnects a circuit or appliance so it can be worked on safely.

A 3-D style drawing with axes at 30° and lengths to scale, used to show pipework layouts.

Clearing a drain using high-pressure water.

The Joint Industry Board — set up to improve relations between plumbing and electrical employers and staff, negotiating fair pay and conditions and resolving disputes.

A powered saw with a reciprocating blade for cutting curves and openings in timber and boards.

Document detailing requirements and standards for a job.

The trade that makes and fits timber components such as doors, frames and floors.

Copper → compression or soldered (end-feed, solder-ring). LCS → threaded, welded or compression — cannot be soldered. Plastic pressure (PB/PEX/MDPE) → push-fit or compression, needs inserts. Drainage: uPVC/ABS/MuPVC can be solvent-welded; polypropylene is push-fit only.

A paste applied to threads/joint faces to help seal a joint; must be approved where it meets drinking water.

The SI unit of energy, including heat energy; one watt equals one joule per second.

An enclosure where cables are joined safely behind covered terminals.

The type of oil used in domestic oil boilers.

Noise caused by scale buildup creating steam bubbles.

A small bend formed near the tube end to bring it across to a fitting or backplate. (Also known as a half passover.)

A prefix meaning a thousand; e.g. 1 km = 1,000 m.

Kilowatt (1000 W).

A leaning ladder for access or short-duration work, set at roughly a 75° (1:4) angle and secured.

A leaning ladder should be set at a 1:4 ratio (about 75 degrees) and project at least 1 m above the access point.

Ladders graded by load: Class 1 up to 175 kg, Class 2 up to 150 kg, Class 3 up to 125 kg; only Class 1 should be used on site.

Heat absorbed or released during a change of state, such as melting or boiling.

Low Carbon Steel.

A union that must be fitted on a full LCS circuit to allow it to be connected and later broken for maintenance.

A toxic metal; both lead dust/solid and lead fume are hazardous and need controls when worked.

A proprietary fitting used to connect lead pipe to other materials such as copper, PB and MDPE.

A mesh/guard fitted to gutters to keep out leaves and debris.

Bacteria that grows in stagnant warm water.

A law or set of laws in force, such as the Health and Safety at Work Act.

To keep in touch and share information so a job runs smoothly.

A final circuit, usually wired in a loop, supplying lighting points and switches.

Calcium carbonate deposits formed from hard water.

The boundaries on what a worker may do based on their level — apprentices, Level 2 and Level 3 staff have different authority, with supervisors and managers carrying more responsibility.

Increase in length when a material is heated.

Paper that changes colour depending on the PH of a substance, used to test whether it is acidic or alkaline.

The unit used to measure capacity; 1 m³ of water contains 1,000 litres.

The body responsible for enforcing health and safety in premises such as shops, offices and hotels (with the HSE), and for ensuring building work meets the Building Regulations — employing a Building Control Officer to monitor builds.

The supplier's large main (often over 100mm) that feeds many houses through individual connections.

Heater sited at or near the outlet (e.g. under-sink, instantaneous) to cut dead leg.

A lock and clip that secures an isolator off so the supply cannot be turned back on.

The balancing valve on a radiator's return, set once to control flow and usually capped.

A radiator with a guarded casing kept cool to touch, used where vulnerable people may contact it.

Liquefied Petroleum Gas.

A WC unit with a rotating blade and pump that grinds waste and pumps it through small-bore pipe to the stack, letting a WC be sited far from or below the stack; supplied via an unswitched fused spur and cannot be the only WC in a property.

Fitted to the return before the boiler; catches ferrous (iron) sludge/magnetite. With corrosion inhibitor it prevents recurring sludge build-up.

The supplier's incoming cable bringing electricity into the property; everything up to the main switch is the supplier's responsibility.

The company responsible for the overall day-to-day running of a construction site.

The conductor connecting the consumer unit and supply to the main earthing terminal, run in a minimum of 16 mm2 cable. Also known as Main Equipotential Bonding

The central terminal where the installation's earth connections are brought together.

Bonding incoming metal services (gas, water) to the main earth terminal. Main protective bonding conductor 10 mm²; main earth conductor 16 mm². Clamp within 600 mm of the service entry, on metallic pipe only.

The switch in the consumer unit that isolates the whole installation; everything after it is the homeowner's responsibility.

Planned schedule of future maintenance tasks.

A record of maintenance carried out on a system, kept on large installations so future faults and patterns can be reviewed.

A plan detailing what maintenance tasks will be carried out, and when they are scheduled — used for planned preventative maintenance on larger installations.

The ability of a material to be hammered or rolled into shape without breaking.

Required by law or rule; compulsory.

An access point into the underground sewer pipework, usually where pipes join the main sewer, that lets you reach the pipe to clear blockages; it is treated as a confined space.

A fitting that lets many small microbore pipes connect to the main 22mm flow and return runs.

A compression joint (Type B) where the pipe end is swaged (opened up) to grip; usable above and below ground; for R220/R250 copper only, not R290.

A U-tube gauge used to measure the small air pressure when soundness-testing drainage.

Moving loads by hand; done as a single lift, two-person lift or with mechanical aids to avoid injury.

Regulations requiring risks from lifting and carrying loads to be avoided or reduced.

A radiator valve adjusted by hand, without a temperature sensor.

The appliance-specific information telling you how to install a particular piece of equipment safely.

Information produced by a manufacturer — the brochure, schedule, installation instructions, service and maintenance instructions, and user instructions (which must be left with the customer).

One of the gases (with propane and butane) that makes up LPG.

Measuring and marking the position of pipework, fixings or cuts before work begins; pipework is normally measured centre-to-centre.

The amount of matter something contains, measured in grams (g); one litre of water has a mass of 1 kg.

The WRAS directory of approved fittings that resist corrosion and avoid contaminating water (lead and lead solder are not allowed on water systems).

Paid time off around a child's birth — up to 52 weeks' maternity leave (with up to 39 weeks' Statutory Maternity Pay if qualifying) and one or two weeks' paternity leave with Statutory Paternity Pay.

Anything you can physically touch or feel — a solid like wood, a liquid like water, or a gas like air.

Water is densest at about 4 °C; below this it expands, which is why ice floats and pipes can burst.

Miniature Circuit Breaker — auto-disconnects on overload/short circuit; resettable (unlike a fuse). Typical ratings: 6 A lighting, 16 A immersion, 32 A ring final; plug fuse 3 A.

Blue medium-density polyethylene pipe used for the underground supply into a dwelling.

A flexible retractable tape for measuring longer pipe runs and marking out installations.

A document describing how a task will be carried out safely, step by step.

Pressure expressed as the height of a column of water; about 1 bar per 10 metres.

A Mobile Elevated Work Platform — a powered machine that raises a worker on a platform.

Pipework run in 22mm to a central manifold, then reduced to 8mm or 10mm out to the radiators.

A motorised three-port valve that can feed heating, hot water or both (used in Y-plan).

A steel used for some heating pipework; needs corrosion protection (inhibitor) in the system.

A prefix meaning a thousandth; e.g. 1 mm = one 1000th of a metre.

A compact scissor-type bender for microbore copper tube.

A shower that blends hot and cold water, which can be fed from the mains, from storage, or from a pumped supply.

A tap blending hot and cold; some mix in the body (needing single check-valve protection) and some are twin-flow.

A wheeled scaffold tower giving a working platform with guard rails for medium-duration work at height.

One of the scales used to measure the scratch-resistance (hardness) of a material.

Two or more atoms bonded together — the smallest amount of a compound that still behaves like that compound.

An electrically operated valve that divides the heating into zones, available as a two port or three port valve and driven by a synchronous motor.

Bringing together skills from different trades or professions to solve a problem that one trade could not handle alone.

Cable with several cores, used especially for wiring central heating control systems.

An instantaneous heater serving several outlets.

Megohm — one million ohms.

A clip fixed with a masonry nail, used for copper and plastic pipe.

The gas normally used in boilers (also known as methane), with a calorific value of 38–39 MJ/m³.

An incident that could have caused harm but did not; reported so the cause can be put right.

Pump that operates even when above cistern level.

A small indicator light on a spur or switch that shows when it is on.

The point where the primary cold feed enters an open vented system; the pump is fitted just after it so the system runs under positive pressure.

The National House Building Council, which sets construction standards and provides warranties for new-build homes.

A voluntary regulatory body that assesses and registers electrical contractors against recognised standards.

A flexible closed-cell pipe insulation used on heating and chilled pipework.

An inert gas used for pressure-testing pipework because it is dry and non-reactive.

A metal without iron (e.g., copper, brass, aluminium).

A compression joint (Type A) sealed by an olive pressed onto the pipe; above ground only; suits copper, PB and PE.

A tap whose spindle does not rise as it is opened; maintenance is usually replacing the washer or the O-rings.

A hot water system that heats water instantly as it flows through the appliance, such as a combi boiler or electric shower.

Cutting a small notch in the top of a joist to run pipe; size and position are limited by Building Regulations to keep the joist strong.

Running pipe through structure within safe limits: vertical chase ≤ ⅓ wall thickness, horizontal ≤ ⅙. Joist notch depth ≤ ⅛ of joist depth (0.07–0.25 of span from support); drilled hole ≤ ¼ of joist depth (0.25–0.4 of span); don't notch/drill joists shallower than 100 mm. Drilling weakens a joist less than notching.

National Vocational Qualification — Level 2 to work as a qualified plumber, Level 3 to supervise.

The bent section of rainwater pipe that connects the downpipe to the running outlet, bridging the gap between the gutter and the wall.

A pair of bends that step the run sideways to a parallel position to line up with a fitting or wall.

The body that supervises the water authorities and ensures customers get value for money from the companies supplying water and removing sewage.

A decorative moulded-profile rainwater gutter.

The unit of electrical resistance.

V = I × R.

A heating layout where flow and return share one pipe, so radiators cool progressively along the run.

A switch that controls a circuit from a single position.

An appliance that takes combustion air from, and may release fumes into, the room it is installed in.

A safety pipe giving expanding water/steam a path out. Never valved; terminates above the cistern; minimum 22 mm; the primary open vent rises at least 450 mm above the F&E cistern to prevent pumping over.

Spoken communication such as conversations, phone calls and toolbox talks.

The seat inside a float valve that the piston closes against; a small orifice suits high pressure and a larger one suits low pressure.

A single point water heater design where opening the outlet tap operates a flow switch that turns on the heating element.

A bidet supplied above the rim, which can be connected to the mains because the outlet stays above the spillover level.

A safety thermostat that switches off the heat source if the water gets too hot (about 85-90C), preventing the water boiling.

Excess current flowing in a circuit.

Substances that release oxygen and intensify a fire, shown by the oxidising hazard symbol.

A high-temperature gas mixture used for brazing/welding; needs flashback arrestors and careful handling.

A trap with a horizontal outlet that holds a water seal to keep drain smells out.

The packing around a stop valve spindle that can be repacked to cure a valve passing water.

The fitting that connects a WC outlet to the soil pipe, available in straight, bent, angled, offset and flexible types.

Unwanted natural circulation of hot water that wastes energy; avoided by pipe layout/insulation.

The part of the Building Regulations covering structure, relevant when notching or drilling joists to run hot water pipework.

The part of the Building Regulations covering hygiene, hot water safety and water efficiency.

The part of the Building Regulations covering heating appliances, including boiler positioning and flueing.

Building Regulations covering energy efficiency, affecting cylinder insulation and controls.

The part of the Building Regulations covering safe electrical work in dwellings.

A system mostly separate but with some rainwater allowed into the foul drain.

The SI unit of pressure; one newton per square metre.

The method for using a fire extinguisher: Pull, Aim, Squeeze, Sweep.

A double bend that lets one pipe pass fully over another while staying on the same line.

Portable Appliance Testing.

Testing how the system performs under maximum demand, recording pressure and flow with all outlets open, checking temperature at outlets etc.

Testing how the system performs under maximum demand. Filling up all appliances and letting them go/flushing them all at the same time. Check trap seal after (should be a minimum remaining of 25mm). Repeat 3x.

Hardness that boiling will not remove; needs treatment such as a softener.

A formal document authorising high-risk work (e.g. hot work, confined space) under controlled conditions.

Allowed or authorised.

A scale measuring how acidic or alkaline a substance is; distilled water is PH 7 (neutral), 0–6.9 is acidic and 7.1–14 is alkaline.

A screw with a cross-shaped recess allowing more torque than a plain slot.

A proprietary fitting that connects almost any pipe material to another using different-sized inserts placed in the body before connecting.

The ratio of a circle's circumference to its diameter, approximately 3.14, used to find the area of a circle (πr²).

A tap that connects to the water supply from underneath, passing through the appliance — the most common type of tap.

Scanner used before drilling or chasing to locate hidden pipes and cables, so you don't drill into a service or a cable safe zone.

The shaped part of a bender that forms the pipe curve.

Forming bends without kinking: the former is the curved channel the pipe bends around; the back guide holds the pipe against it; minimum bending radius ≈ 3× pipe diameter (15 mm copper, spring). LCS is elastic, so it's overbent by 5° to allow for springback.

Securing waste pipe at set intervals to stop it sagging and keep the correct fall; clip types include the overflow push-in/nail-in clip, the waste pipe saddle clip and the soil pipe clip.

Identifying pipe by colour: MDPE supply pipe is blue; heavy-grade LCS is red and used for heating. Helps recognise material and use on site.

A tool with a cutting wheel that scores and cuts tube, leaving a square end; the burr (ream) is then removed.

A tool that freezes a plug of water in a pipe so work can be done without draining the system.

Adjustable plumbing pliers used to grip and turn pipe, nuts and fittings.

A sleeve pushed into the end of soft pipe (PB, PE, large-bore R220) so a compression or push-fit joint cannot squash and release it.

A thermostat on the boiler return (set about 25C) used with a frost thermostat to switch the system off once the pipework has warmed.

A channel cut into a wall to recess pipework

Localised corrosion found most often in hard water areas, also caused by too much flux or stray electrical current on the pipework.

A scaled drawing of the layout viewed from above, used to set out an installation.

Scheduled maintenance carried out at regular intervals to prevent breakdowns, regardless of whether a fault has occurred.

The trade that applies plaster and render to walls and ceilings.

The plastics used for above-ground drainage — polypropylene (PP), ABS, PVC, uPVC and MuPVC — which look similar but differ in UV resistance and jointing; PP has a different external diameter and joints only by pushfit or compression.

Tube such as polybutylene (PB) or polyethylene; flexible types are clipped or cold-formed, while rigid plastics change direction with fittings.

The soundness test for plastic pipe (polybutylene, MDPE), carried out as Test Type A or Test Type B rather than the rigid pipe procedure.

Standard British Standard symbols on drawings representing pipework, fittings and appliances.

A low platform with full guard rails giving a safe, stable work position at modest height.

A molecule with one slightly positive side and one slightly negative side, causing water molecules to stick together like tiny magnets.

Confirming live and neutral are connected the right way round so switches and fuses are in the live conductor.

A ladder with a pole each side carrying the rungs, used for access or short work only.

A flexible plastic pipe material that degrades in UV (sunlight) unless treated.

The main component of MDPE pipe; a plastic that degrades in UV (sunlight) unless treated.

The pressure on each side of the pump — positive in front as it pushes, negative behind as it pulls; the pump is sited so the system runs mostly under positive pressure.

The amount of energy carried in a circuit, measured in watts (symbol P); often given in kilowatts (1 kW = 1000 W).

The relationship between power, current and voltage: P = I x V; used to work out things like the correct fuse size.

Faults making a power tool unsafe: frayed lead, damaged plug, mechanical damage, missing safety features — remove from use and report.

Forcibly flushing the whole system to clear sludge when several radiators are affected.

A cross-head screw with extra radial points that grips better and reduces cam-out versus Phillips.

Personal Protective Equipment.

Regulations requiring employers to provide and maintain suitable personal protective equipment free of charge.

Water falling from the atmosphere as rain, snow, or hail.

A fitting that looks like a solder-ring fitting but seals with a rubber O-ring crimped onto the pipe by a pressing machine — no heat.

The 'push' that forces water through pipes; scientifically, force applied over an area, measured in Pascals (Pa), bar or N/m².

An instrument used to measure water pressure at the outlets during performance testing, or as the system is working.

One of the two types of oil fired boiler (the other being vaporising).

A valve fitted on a high-pressure supply pipe to reduce the pressure where required.

The pipe from the F&E cistern that fills the heating system and lets it expand; no valves are fitted on it.

The pair of pipes carrying water to and from the boiler around the heating circuit, including the cylinder coil; minimum 22mm (28mm on solid fuel).

The vent on an open vented heating system that keeps it at atmospheric pressure and lets water expand into the F&E cistern; minimum 22mm, no valves.

The pipework carrying water to and from the boiler through the heating circuit, including to the coil in a storage cylinder.

An above-ground drainage stack that vents through the open top, with no separate vent pipes.

Any water supply not provided by a water company, such as a borehole, spring or watercourse, filtered and treated on site.

Behaviour that reflects positively on you and your trade.

A room thermostat that also lets different temperatures be set at different times; recommended as best practice in the CHeSS.

A document that sets out when each part of the work will be carried out so the job runs in a logical order.

A timing device that sets when the heating and hot water turn on and off.

A legal notice that stops work immediately where there is a serious risk of injury.

The person responsible for planning, running and delivering the project on time and budget.

A liquefied petroleum gas (LPG) used for heating and blowtorches; heavier than air so it sinks.

A sleeve used to protect the supply pipe where it passes through the foundations of the property.

Prove the tester on a known live source → test the circuit is dead → prove the tester again, confirming it didn't fail mid-test.

A device used to prove a voltage indicator works before and after testing (prove-test-prove).

Thread-sealing tape wound onto threads to seal a threaded joint.

A cord-operated switch used in bathrooms where a wall switch is not permitted near water.

A device used to circulate water or boost pressure to a shower or long hot water run; fitted with full bore service valves.

A system where a pump circulates water around the heating circuit.

A shower boosted by a pump to raise the flow and pressure from a stored system.

The pump forcing water up the open vent into the cistern — wastes heat, draws in cold water and introduces oxygen (corrosion). Prevented by close coupling: cold feed and open vent within 150 mm of each other at the neutral point, same side of the pump.

A clip the pipe pushes into; commonly used for copper and plastic where appearance matters less.

Joint using an O‑ring and grab ring; requires pipe inserts for plastic.

A scaffold with one side supported by the building wall, which cannot stand on its own.

Provision and Use of Work Equipment Regulations — work equipment must be suitable, maintained and used by trained people.

A light, corrosion-resistant plastic that deforms if overheated and degrades in UV (sunlight) unless treated.

One of the two main pipe insulation types, alongside expanded nitrile rubber.

Judging risk by sorting it into descriptive levels such as low, medium and high.

The person who manages the costs and quantities of materials and labour on a project.

An isolation valve opened or closed with a quarter turn of a lever.

A quotation is a fixed price for proposed work. An estimate is an approximate price that may change.

A test measuring resistance between line and earth to find the overall resistance of a circuit.

Soft copper supplied in coils; suitable for hand bending.

Half‑hard copper supplied in straight lengths; most common for plumbing.

Hard copper supplied in lengths; not suitable for bending.

Circuit that runs from the consumer unit to outlets without returning.

Heat transfer by electromagnetic waves without needing a medium.

A small key used to open the air vent and release trapped air from a radiator.

A spanner (often ½" hex) used to tighten radiator valve tails and unions.

The distance from the centre of a circle to its perimeter; half the diameter.

Collecting and reusing rainwater to reduce demand on treated mains water.

A brand-style expansion bolt that grips masonry as it is tightened, for heavy fixings.

Residual Current Breaker with Overload protection.

Residual Current Device — detects earth-fault current and trips, but does NOT protect against overload (an RCBO does both). A 30 mA RCD trips within milliseconds — standard near water (bathrooms).

Changes an employer must make so a disabled person can work or keep working, such as providing wheelchair access to the workplace.

A 110 V centre-tapped supply used on site to lower the risk of serious electric shock.

A fitting that reduces the pipe size (e.g. 28 mm to 15 mm); available as straight or bent reducers, and as reducing tees.

Dismissal handled under the Employment Relations Act, which requires fair and reasonable grounds and sets minimum notice periods based on length of service.

Density of a substance compared to water.

Natural gas (methane) RD ≈ 0.7 — lighter than air, a leak rises. LPG (propane/butane) RD > 1 — heavier than air, a leak sinks to floor level. Drives where you detect and ventilate.

A form filled out to request materials, which the company's buyer then uses to order them.

An above-ground stored water source; treated water is also held in a service reservoir before distribution.

Masks and respirators that protect the lungs from dust, fumes and fibres; must be the correct type and fit.

A ring fitted to a shower hose to keep the head above the spillover level, providing an air gap against backflow.

An older fuse with a replaceable fuse wire; less accurate and now largely superseded by MCBs.

An older fuse with a replaceable fuse wire that burns out and snaps if too much current flows; the wire is rewired by hand.

Reporting of Injuries, Diseases and Dangerous Occurrences Regulations.

A death, specified major injury, dangerous occurrence, or injury causing over 7 days off work.

The soundness test for rigid pipe (copper, LCS, stainless steel): fill, stabilise, pressurise to 1.5x working pressure and hold for 1 hour, checking for any pressure drop.

Circuit that starts and ends at the consumer unit forming a loop.

A tap where the head rises visibly as the tap is opened; also known as a screwdown tap. The seal is made by a washer on a seat.

The likelihood of harm occurring and the severity of the outcome.

A systematic review that identifies hazards, evaluates risks, and sets control measures.

A way of putting a number on risk by multiplying how likely harm is by how serious it would be.

A scoring method where likelihood and severity are each rated 1-5 and multiplied to give a risk factor, so the highest risks get the most control.

Clearing a drain or branch by pushing drain rods through it.

A layer fitted below the roof covering to catch any water that gets past the slates or tiles and let it run off into the gutter.

A ladder that hooks over the ridge to spread load when working on a pitched roof.

A solid fuel appliance that burns wood or coal to heat a single room.

A boiler that takes combustion air from and discharges its products to the outside, working independently of the room's air.

A thermostatically controlled switch that turns on the pump and boiler when heating is called for; in a new property it must be in the main living area, about 1.5m up and away from heat.

A pine-tree resin used in some soldering fluxes; its fumes can irritate the airways and lead to occupational asthma.

A screw with a domed head that sits on the surface rather than flush.

Reduced Pressure Zone valve for high‑risk backflow protection. Protects up to Fluid Category 4, and may be used on commercial heating systems or other commercial use such as dishwashers or washing machines.

A rubber fitting that protects a cable where it passes through metalwork, such as a metal back box.

The gutter fitting that the water runs towards and drops down into the downpipe; the gutter is laid to fall towards it.

A trap fitted in a horizontal run rather than directly under an appliance.

A fully pumped control layout using two two-port motorised valves for separate heating and hot water.

A trap with a vertical (downward) outlet that holds a water seal.

A more reactive metal connected to the metal being protected; it corrodes preferentially so the protected metal stays intact. In cylinders the anode is usually aluminium or magnesium.

Ensuring a supply is disconnected, proved dead and cannot be re-energised: isolate, lock off with a unique key, prove dead with an approved voltage indicator using Prove–Test–Prove (testing Line–Neutral, Line–Earth, Neutral–Earth), keep the removed fuse in your pocket, post a warning notice. For consumer-unit work, isolate at the main switch.

An agreed method of doing a task that has identified the hazards and built in controls to remove or reduce risk.

Follow the manufacturer's instructions, stay aware of surroundings and others, use the right PPE and the right tool.

The built-in cut-out within an immersion thermostat that switches off the element if the temperature rises too high.

A document supplied with a hazardous product setting out its risks and safe handling, storage and emergency measures; used to inform a COSHH assessment.

The four sign types: mandatory (blue), prohibition (red), warning (yellow) and information/safe-condition (green).

Pipe / appliances / fall / max distance to stack: 32 mm (basin, bidet, single-bowl urinal) 18–45 mm/m, 1.7 m · 40 mm (bath, shower, sink, dishwasher, washing machine, slab & trough urinal) 18–90 mm/m, 3 m · 100/110 mm (WC) 18–90 mm/m, 6 m. Max distances prevent self-siphonage.

The sealant used when bedding waste fittings and appliances: putty or silicone can be used on ceramic or steel sanitaryware, but on plastic sanitaryware only silicone should be used, because oil-based plumbers' putty degrades the plastic and shortens the appliance's life.

A TMV delivers a preset safe temperature — typically 43°C, maximum 48°C for a bath under Building Regs Part G. If the cold supply fails, the TMV fails safe and shuts off the hot to prevent scalding.

Calcium carbonate deposits from hard water.

A drawing produced to a set ratio such as 1:50 or 1:20; if a size is written on the drawing, always use the written size rather than scaling it off.

A contract document that tells you what must be fitted in each property.

A hand-operated bender for small copper tube (15/22 mm) using a scissor action against a former.

A MEWP that raises a platform straight up on a folding (scissor) mechanism.

The first treatment stage, passing water through a screen to remove larger debris such as litter and sticks.

Reasons to choose screw materials: longevity, cost, hygiene, corrosion resistance and safety (e.g. brass/stainless in damp areas).

A hand tool for driving/removing screws; the tip must match the head (slotted, Phillips, Pozidriv).

A drill with an SDS chuck and hammer action for drilling into brickwork, concrete and (with the right bit) metal.

Jointing and gap-filling compounds that may irritate skin or give off fumes until cured.

A heating system with no F&E cistern, filled and pressurised from the mains via a filling loop. An expansion vessel absorbs expansion; system pressure ~1 bar cold. Reaching ~3 bar hot points to a faulty/undersized vessel.

Loop keeping hot water circulating for instant delivery.

The pipe from the CWSC to the cylinder, minimum 22mm, with a valve so the cistern need not drain for cylinder maintenance.

The vent on an open vented cylinder that keeps it at atmospheric pressure and lets water expand into the CWSC under fault conditions; no valves.

The pumped return of a secondary circulation system, fitted with a non-corrosive (bronze or stainless) pump and re-entering the top third of the cylinder.

A system with a separate parallel vent stack cross-connected to the discharge stack.

The usable hot water stored or heated in the cylinder for the taps, kept separate from the primary heating water.

A system that heats only selected parts of the property.

The minimum flow velocity (and so minimum gradient) needed to keep solids moving so the drain doesn't silt up.

A system where the heating is pumped but the hot water circulates by gravity; the boiler-to-cylinder pipework is a minimum of 28mm.

Heat that causes a temperature change without a change of state.

A substance that can cause an allergic reaction after repeated exposure.

A below-ground system with separate pipes for foul water and rainwater.

The supply pipe from the boundary to the dwelling, the property owner's responsibility.

A raised store of treated water (often on a water tower) that gives pressure for distribution to homes via the cold main.

A small in-line valve that isolates an individual appliance or tap for maintenance.

A tank in the treatment process where water is held so small particles can settle out after screening.

Harmful infections that can be caught from contact with sewage — including Hepatitis, Tetanus, bacterial infections such as E. coli and Leptospirosis (Weil's disease) — entering the body by inhaling, swallowing, or through cuts and grazes.

A force where two forces push or pull but are not directly in line with each other.

A material's resistance to shear force, where two forces push or pull but not directly in line with each other.

The fitting at the bottom of a downpipe that directs rainwater away from the wall, often discharging over a gully.

A pump used to boost a shower; some boost only the hot supply and some boost both hot and cold.

The shower head from which water is delivered; poor flow through it can be caused by a blocked strainer, faulty cartridge or limescale.

A cutting tool used to cut domestic cable and conductors to length.

Dust from brick and cement, the second biggest cause of occupational lung disease after asbestos; a hazardous substance under COSHH.

A backflow device with one check valve, used e.g. on a mixer tap mixing in the body.

A valve that lets the flow and return connect to the bottom of a radiator at the same end (BSE).

A shower pump that boosts either premixed water or just the hot supply (with cold from the mains) to achieve a good flow rate.

An indirect cylinder with one heating coil, e.g. heated by a boiler.

The supply normally provided to a domestic property, using one line and one neutral.

An instantaneous heater serving one outlet, e.g. over a sink.

Cylinder fed from a cold water storage cistern, that fills the primaries (heating) pipework inside the cylinder.

Kitchen sinks by bowl arrangement (single bowl, double bowl, bowl-and-a-half) and the deep ceramic butler sinks — the London pattern with no built-in overflow and the Belfast with a built-in overflow.

The flow of liquid up and over a high point and down the other side, started by pressure difference.

On site, supply is colour-coded by voltage: 110 V yellow, 230 V blue, 400 V red.

One of the first people on site, responsible for setting out, short-term planning, liaising with staff, monitoring safety and contributing to method statements and risk assessments.

The person supervising work and workers on site day to day.

A transformer used on site to step 230 V down to the safer 110 V used for tools; coded yellow.

A low convector heater that runs along the skirting line of a room.

Passing pipe through a protective sleeve where it crosses a wall or floor, allowing movement.

A screw with a single straight slot, driven with a flat-blade screwdriver.

A treatment stage where water is filtered through sand and charcoal to remove the smallest particles.

The build-up of rust and debris in a heating system that causes cold spots, especially at the bottom of radiators.

A leak-location method that forces smoke into the pipework so escapes can be seen; it must not be used on plastic pipework because the smoke damages the plastic.

A pit that lets surface (rain)water soak into the ground, used where there's no surface-water sewer. (Not used for foul water.)

A plug-in device that checks a socket's wiring and indicates faults such as reversed polarity.

Slightly acidic water that reacts well with soap but is corrosive to pipework over time; caused by water falling on ground such as sandstone or moorland.

A fitting that lets several small-bore discharge pipes connect to the stack at one point, which also reduces the risk of crossflow.

Vertical discharge pipe. Primary ventilated stack — one vented stack, all branches connected (most common). Secondary ventilated stack — extra vent pipe alongside. Ventilated branch discharge — each branch vented. Stub stack — short, not vented to atmosphere, uses an AAV. Stack ≥ largest branch; min 75 mm vent; terminate 900 mm above any opening within 3 m; opposing branches separated 200 mm to prevent cross-flow.

Using roof collectors to heat water from the sun, usually via a coil in a cylinder.

A capillary joint: cut and deburr, clean pipe and fitting, flux the pipe, heat the fitting and run lead-free solder in (solder-ring fittings already contain solder); wipe off flux to stop corrosion/green staining.

Risks when soldering: burns and fire (lay a damp cloth to protect nearby plastic clips/fittings), flux that irritates skin, and explosion near flammable gases; use PPE, a heat mat, an extinguisher and ventilation.

Copper fitting containing pre‑loaded solder.

A fuel such as wood, wooden pellets (biomass) or coal (anthracite) that burns continuously and needs a heat leak to dump surplus heat.

Water's ability to dissolve other substances; dissolving substances in water changes its PH.

Chemical bonding of plastic pipes using solvent cement.

Cleaning and easing fluids that can be harmful, flammable or irritant; use with ventilation and PPE.

Pressure testing a system for leaks before commissioning.

Energy to raise 1 kg of a substance by 1°C, in kJ/kg°C. Water = 4.186; copper = 0.385. Heat energy: E = mass × SHC × temperature change.

A plug-type isolation valve that cannot be maintained and is replaced rather than repaired if it passes water.

The plain, unprepared end of a pipe that pushes into a socket or fitting.

A below-ground water source where groundwater flows naturally to the surface.

A hollow-wall fixing whose spring-loaded wings open behind plasterboard to spread the load.

Single branch taken from a ring final circuit.

The dry upper part of a soil stack that lets air move in and out; it must be at least 75mm and terminate at least 900mm above, or 3m horizontally from, any opening into the building.

Payments made at agreed points in a project, normally on completing a stage such as the foundations or making the building watertight.

Water standing too long in oversized or low-turnover cisterns, allowing algae and bacteria to grow.

A corrosion-resistant alloy with little magnetism that does not rust, so it is not considered ferrous and can be used for water supply.

A ladder accessory that holds the ladder clear of the guttering so it rests off the gutter, preventing damage during maintenance.

A clip used to fix insulated pipework in a visible position.

The three states of water — solid (ice), liquid and gas (steam/vapour) — depending on temperature.

Pressure when water is not flowing.

Pay from your employer when off sick for four or more consecutive days with a certificate; self-certification covers up to 7 days, beyond which a doctor's medical certificate is needed.

A compression fitting designed to joint low carbon steel tube without threading or welding.

A rigid metal ruler used to measure and mark tube accurately before cutting or bending.

A self-supporting A-frame ladder for short-duration work at low height.

A transformer that lowers the supply voltage to the level needed; electricity leaves the power station at around 400,000 V and is stepped down at transformers before it reaches the property.

A plate that supports a float valve in a plastic storage cistern so its operation does not damage the cistern over time.

A fitting used to close off an open end of pipework.

A screw-down valve that isolates the supply; the main stop valve controls water into the dwelling.

A hot water system that holds a supply of heated water within it, such as a system with a cylinder.

Fitting allowing cylinder connection and disconnection.

A component cleaned and checked during maintenance to remove debris from the water.

Layering of hot water at the top and cold at the bottom.

An elbow (90° or 45°) with one male and one female end, letting it screw or push straight into another fitting.

How resistant a material is to being damaged by the forces acting on it — including compressive, tensile and shear strength.

The engineer responsible for the strength and stability of the building structure.

A short un-vented stack serving close-coupled appliances, capped with an air admittance valve.

A company hired by the main contractor to carry out specific work.

The Sector Skills Council for the building services sector, which finds out the skills employers need and writes the specifications that the awarding body (e.g. City & Guilds) turns into a qualification.

Bonds extraneous metal parts together in special locations (e.g. bathrooms) so they stay at the same potential during a fault. Conductor 4 mm².

Unit containing the main service fuse.

Legislation protecting consumers against bad workmanship, requiring work to be carried out with reasonable care and skill, in reasonable time and at reasonable cost.

The run from main to property: communication pipe (main → boundary, owned by the water undertaker), external/boundary stop valve (operated with a crutch key), then the service pipe (boundary → property, owned by the owner) to the internal stopcock.

A remote/slide-operated stop valve ('water fuse') that isolates the supply without a traditional stopcock.

The skin-like film on water's surface caused by cohesion between water molecules at the surface.

Water collected from lakes, reservoirs, rivers and streams before treatment.

A professional who measures, values or inspects buildings and land.

Safe Working Load.

The small synchronous motor inside a motorised valve that drives it open; replaceable as a unit.

A boiler for sealed systems with the pump and expansion vessel built in, but still feeding a separate hot water cylinder.

A fitting used to connect a draw-off pipe to a cistern or tank.

A fitting connecting pipework to a tap or appliance tail; flexible types seal on a rubber washer, rigid types on a fibre washer.

Re-cutting a damaged tap seat so a new washer can seal properly.

A radiator connected at the top one end and bottom the other, improving convection; common on old one pipe systems.

A T-shaped three-way fitting; equal tees have all legs the same size, reducing tees have a smaller leg. Describe the branch (middle) leg last, e.g. 28-28-35.

A ladder whose sections slide together for storage and extend for use; checked before each use.

How hard or soft a metal is; copper tube comes in different tempers, from soft (annealed) to half-hard.

A safety valve on an unvented cylinder that discharges if the water gets too hot.

Bond used to maintain earth continuity when cutting metal pipework.

Hardness that can be removed by boiling, which deposits scale; caused by dissolved calcium bicarbonate.

To put forward a price or quotation to win a job or contract.

A pulling force, where two forces pull directly away from each other.

A material's resistance to being pulled apart (stretched) before it fails.

A cage fitted to a stack terminal to keep out birds and debris.

Metallic heating pipework is pressure-tested to 1.5× the maximum operating pressure. Cleanse → neutralise → add inhibitor.

The comfortable temperature a heating system is designed to provide, which is its main purpose.

A material that allows heat to travel through it easily, such as silver, copper or steel.

A material that resists heat flow, used to lag pipes and cylinders to save energy and prevent freezing.

The minimum legal scald protection on an older semi-gravity system where a thermostat and zone valve are not fitted.

An exposed bar-type shower valve with a thermostatic cartridge, fed with a balanced supply.

The replaceable cartridge inside a thermostatic tap, shower or mixing valve that controls the blended water temperature.

A valve that blends hot and cold to a safe, stable outlet temperature to prevent scalding.

A joint made by screwing threaded pipe/fittings together, sealed with PTFE or compound; common on LCS.

A cable like twin and earth but with three insulated cores plus an uninsulated earth, used e.g. for two-way lighting.

Keeping three limbs in contact with a ladder when climbing, so a slip can be caught.

A UK plug with live, neutral and earth pins and a cartridge fuse, wired to the correct colour code.

A motorised valve that directs flow to either heating or hot water (priority).

The inside face of a bend — the tighter, compressed curve on the inside of the radius.

A small ripple or indentation left on the throat of a bend when the bending machine forms it.

The trade that fixes wall and floor tiles.

A shoring system built from timber sheeting, struts and wales to support trench sides.

A record of the hours a worker spends on jobs, used for pay and costing.

A combined neutral-and-earth supply (PME) where the earth is taken from the supplier's neutral at the cut-out.

An earthing system where the supply provides a separate earth conductor all the way back to the source.

A board fitted at the base of a working platform to stop tools and materials being kicked off the edge.

Floorboards with interlocking edges; lifted carefully for access to pipework.

A short, informal on-site briefing on a specific health, safety or working-practice topic.

A washer used to support a pillar tap through a flexible surface such as a stainless steel or plastic sink.

A radiator shaped as a heated towel rail, common in bathrooms.

Substances that can cause serious harm or death if inhaled, swallowed, or absorbed (could be described as poisonous).

An electric heating tape along a hot pipe that keeps water hot and cuts dead-leg waste.

An organisation that promotes standardisation in an industry and supports members with subsidised training, advice and representation.

The person supervising a particular trade's work on site.

The very high voltage (around 400,000 V) used to carry electricity from the power station, which reduces the amount lost as heat in the wires.

The depth of water that forms the trap seal. Appliances connected to a soil stack generally need 75mm; the exceptions are baths and showers (flat-bottomed appliances), which need 50mm on a stack or 38mm on a gully, and any appliance on a discharge pipe larger than 50mm, which also drops to 50mm. WC pans have a 50mm seal.

The loss of a trap's water seal, which lets sewer smells into the building. There are nine causes: leakage, evaporation, momentum, capillary action, compression (back-pressure), self-siphonage, induced siphonage, wavering out and crossflow. An anti-siphon trap or air admittance valve admits air to break the vacuum.

A check that the drainage system works by filling each appliance and letting it drain (WCs flushed), then confirming at least 25mm of trap seal remains; repeated at least three times with the trap recharged each time.

Facility where raw water is treated to become wholesome.

Shoring or trench boxes that hold back the sides of an excavation to stop collapse.

A cylinder with three (or more) heating coils so several heat sources, such as a boiler and a solar thermal panel, can each connect separately.

A removable-lid channel that contains and protects cables along a surface.

Thermostatic Radiator Valve — modulates flow into a radiator to hold a set room temperature. Not fitted in the same room as the room thermostat (they'd fight); at least one radiator must have no TRV.

An earthing system where the installation has its own earth electrode rather than an earth from the supplier.

The standard sequence: select material, select the correct machine/former, measure, mark, then bend.

An open fitting with a visible air gap on the discharge pipe of an unvented hot water system, letting any discharge be seen and preventing backflow.

The cloudiness of water caused by tiny suspended particles; a key measure of water quality.

Flat cable containing Live, Neutral and CPC.

A shower pump that boosts both the hot and cold distribution pipework; needs a minimum 150mm head to activate its flow switch.

An indirect cylinder with two coils, e.g. one for a boiler and one for solar.

Tap with separate hot and cold waterways to prevent mixing.

A heating layout with separate flow and return pipes so each radiator gets water at a similar temperature.

A motorised zone valve that opens/closes a single circuit (used in S-plan).

A switch that, paired with another, controls the same circuit (e.g. a light) from two positions.

Low-temperature heating laid in the floor: flow pipe against the external wall first (heat where loss is greatest), kept 100 mm clear of walls, at 200 mm centres. Slow to heat up and hard to retrofit.

Underground cold water service pipe: minimum 750 mm (frost protection), maximum 1350 mm (ground-load damage). 750 mm also applies where an uninsulated pipe enters through a solid floor.

Water drawn from wells, boreholes and springs.

A fused spur with no switch, used for appliances that should not be turned off but still need fuse protection, such as a macerator WC.

Sealed hot water cylinder supplied directly from mains.

A sealed stored hot water system fed at mains pressure, with safety devices to control expansion and temperature.

The component chain on an unvented cylinder: pressure reducing valve → single check valve → expansion vessel → expansion/pressure relief valve → temperature & pressure relief valve → tundish and discharge pipe. Unvented cylinders also need three tiers of temperature protection: control thermostat, non-resetting overheat thermostat, and T&P relief valve.

A sanitary appliance for urine, made as single (bowl), slab or trough types; single urinals discharge through 32mm pipe and slab and trough urinals usually through 40mm.

Damage caused by sunlight that makes plastic drainage pipe brittle with reduced impact resistance; ABS is the most susceptible, while uPVC and MuPVC resist it better.

Disinfecting water with ultraviolet light to kill micro-organisms.

A fault where water keeps flowing past an isolated valve, usually from debris on a gate valve seat or a worn washer.

The seating a washer closes against in a tap or valve; a worn seat can be reground to stop the valve passing water.

One of the two types of oil fired boiler (the other being pressure jet).

A written instruction issued when the client or architect changes the specification, required before the extra work is done; any cost change is agreed between the quantity surveyor and clerk of works.

Speed in a given direction, measured in metres per second (m/s).

A cap fitted to the top of a stack vent in exposed, windy positions to deflect the wind and prevent trap seal loss by wavering out.

A stored hot water system fed from a cold cistern and open to atmosphere through a vent pipe.

A tap on an undersink water heater that also acts as a pressure relief, dripping water as the stored water expands (the drip is a safety feature, not a fault).

A system with extra vent pipes to branches to protect trap seals on longer/loaded runs.

The first commissioning stage: checking pipework is supported and undamaged with no open ends, before and after filling with water.

The unit of electrical pressure (potential difference).

The "push" that drives electricity round a circuit, measured in volts (symbol V).

An approved test instrument used to confirm a circuit is dead during safe isolation.

The amount of space inside a 3-dimensional object, measured in metres cubed (m³); 1 m³ of water contains 1,000 litres and weighs 1,000 kg.

An older fully pumped system using a three port diverter valve, no longer installed from new.

A heavy-duty expanding bolt fixed into masonry for high loads.

A plastic plug pushed into a drilled hole so a screw can grip in masonry or brick.

Pipe that discharges outside if cistern overfills.

An isolation valve fitted before a washing machine or dishwasher so it can be isolated for servicing.

A unit fitted under a sink that grinds food waste; its inlet is larger than a normal sink outlet (about 89mm against 38mm) but it connects to 40mm waste pipe — isolate the electrics and beware the cutting blades when working on it.

The fitting connecting an appliance to its trap and waste pipe — a slotted waste where the appliance has an integral overflow (so the overflow drains into the waste), an unslotted waste where it has none, and a pop-up waste, which drains slowly or fails to seal if its adjusting screw is set wrong.

A device that changes how scale forms (e.g. magnetic/electrolytic) without removing the minerals.

A filter, usually fitted to an individual appliance, that removes limescale particles from the water.

A knocking or banging in pipework caused when moving water is stopped suddenly, such as by a fast-closing valve or a bouncing float-operated valve.

The water company's inspector who checks compliance with the Water Regulations.

Device measuring water consumption to encourage conservation.

The legal requirements for water fittings and systems to prevent waste, misuse and contamination of the supply.

A device, usually using ion exchange, that removes the minerals causing hard water.

Water authorities responsible for supplying and removing water in a region.

A trap using a flexible membrane instead of a water seal to block smells; unlike a water-seal trap it is not susceptible to trap seal loss.

Approved contractor scheme allowing plumbers to self‑certify work.

The unit of electrical power; volts multiplied by amps.

Where a WC cistern sits relative to the pan: high level and low level (joined to the pan by a flush pipe with a ribbed seal) and close coupled (sealed straight onto the pan with a doughnut washer).

The three main WC pan types by how the trap empties: washdown (flush water displaces the trap contents — the most common), single trap siphonic (a narrow trap outlet creates a partial vacuum that sucks the contents out, quieter than washdown) and double trap siphonic (a vacuum forms between two traps, emptying the pan silently).

A serious infection from water contaminated by rat urine; a hazard when working on drainage.

A tool used to measure flow rate when performance testing a system.

A below-ground source sunk into the ground to reach groundwater; a deep well through impervious rock gives cleaner water than a shallow well.

A way of describing a soil stack in two parts — the 'wet' part (main and branch discharge pipes that carry water) and the 'dry' part (the vent above the highest branch, which carries only air).

A heating system that uses water to carry heat from the heat source to the heat emitters.

Tasks involving prolonged or frequent contact with water, which can cause dermatitis; waterproof gloves should be worn.

The way molten solder flows across and grips clean, fluxed copper to form a sound capillary joint.

Water safe for drinking and domestic use.

A hand tool that removes cable insulation without nicking the conductor.

A document showing when different tasks on a project are scheduled to be completed, so all trades can plan their work efficiently.

Avoid work at height where possible; use the safest access. Ladder rules: set at 75° (the 1:4 rule — 1 out at the base per 4 up); extend at least 1 m (≈4 rungs) above the landing. An extension ladder is for access only, not a working platform.

Regulations requiring work at height to be planned, supervised and carried out safely using suitable equipment.

The pressure an open vented cylinder can comfortably handle, in metres; Grade 1 = 25m, Grade 2 = 15m, Grade 3 = 10m.

The pressure in a system when all the outlets are running; important to know before fitting another appliance.

Employment law on hours — workers aged 18+ cannot be forced to average over 48 hours a week (though they can opt out in writing), and under-18s are limited to 40 hours a week and 8 hours a day.

Regulations covering basic workplace welfare such as lighting, temperature, toilets and rest facilities.

A degraded tap washer that causes dripping and is a common cold-water defect.

The Water Regulations Advisory Scheme, which approves plumbing products that meet the Water Supply (Water Fittings) Regulations and publishes the Water Regulations Guide.

Communication in writing such as email, letters and reports, giving a record.

The distance from where the pipe stops inside a fitting to the centre line of that fitting; subtract each fitting's X dimension from the centre-to-centre measurement to get the cut length.

A fully pumped control layout using a single three-port mid-position valve for heating and hot water.