Bathroom Glossary

A physical separation between a water outlet and the flood level of a fixture. Required by UK water regulations to prevent backflow contamination.

A trap designed to maintain its water seal even when negative pressure occurs in the drainage system, preventing the seal from being sucked away.

Methods and devices used to stop contaminated water entering the clean water supply. A UK water regulation requirement for bathroom installations.

A compact, cylindrical trap that sits beneath a basin. Popular in modern installations where pipework is visible, as it looks neater than a P-trap.

A matte, directionally textured surface that hides fingerprints and water spots better than polished finishes. Popular in brushed nickel, brass, and gold.

A traditional toilet design where the cistern sits directly on top of the pan. Simpler to install and maintain than concealed cistern systems.

A combination boiler providing hot water on demand without a storage tank. Affects shower options as it typically delivers lower flow rates than cylinder systems.

A toilet cistern hidden behind a wall or furniture unit, with only the flush plate visible. Requires an access panel for maintenance.

A removable panel or flush plate that provides access to the concealed cistern for maintenance. Must allow access to the fill valve and flush mechanism.

A flexible membrane installed between substrate and tiles that absorbs movement, preventing tiles from cracking due to structural movement or underfloor heating expansion.

High-quality ceramic valve technology used in premium taps. Provides smooth operation and long-lasting drip-free performance.

A valve that redirects water flow between outlets, such as switching between a fixed head and hand shower, or bath filler and shower.

A flush mechanism offering two flush volumes (typically 6L/3L or 4.5L/3L), allowing water-saving smaller flushes for liquid waste.

A metal coating applied through electrochemical process. Standard for most chrome fittings; less durable than PVD but more affordable.

A two-part grout that is genuinely waterproof, stain-proof, and requires no sealing. More expensive and harder to apply, but ideal for wet areas and areas prone to staining.

A ventilation fan that removes moisture and odours from the bathroom. Building regs require mechanical ventilation in bathrooms without openable windows.

The slope of a floor towards a drain, essential in wet rooms to prevent water pooling. UK standard is typically 1:80 (12.5mm per metre).

The initial rough plumbing and electrical work done before plastering and tiling. Includes running pipes, cables, and installing concealed frames.

A device that limits water flow rate, often fitted in taps or showers to reduce water consumption or balance flow in multi-outlet systems.

The visible wall-mounted panel used to activate a concealed cistern flush. Available in various finishes and must be compatible with the cistern frame.

A wall-hung toilet supported by a steel frame built into the wall. The frame also houses the concealed cistern and provides structural support.

Pre-made bathroom furniture such as vanity units, WC units, and storage cabinets. Available in various finishes from moisture-resistant MDF to solid wood.

Mineral deposits (limescale) that build up on fixtures in hard water areas. Dark finishes and textured surfaces show scaling more prominently than polished chrome.

A mains-fed or unvented cylinder system providing 1.5-3+ bar pressure. Allows use of rain heads and multiple shower outlets without pumps.

A humidity sensor that automatically activates an extractor fan when moisture levels rise. More effective than timer-only controls for preventing damp.

Ingress Protection rating indicating water and dust resistance. IP44 minimum for Zone 2, IP65 or higher for Zone 1 bathroom locations.

A valve that allows water supply to be shut off to individual fixtures. Essential for maintenance and repairs without draining the whole system.

Independent European testing and certification body for water industry products. Provides additional quality assurance for products used in UK water systems, often alongside WRAS.

Brass fittings with a clear protective lacquer to prevent tarnishing. Requires gentle cleaning with non-abrasive products to preserve the coating.

A long, narrow drain channel used in wet rooms and level-access showers. Allows floor tiles to slope in one direction only, simplifying installation.

A gravity-fed water system relying on a cold water tank in the loft. Typically provides 0.1-0.3 bar pressure, often requiring a shower pump.

A shower tray with a shallow height (typically 25-40mm), sitting almost flush with the floor. Requires adequate floor void or a raised platform.

Luxury Vinyl Tile—a waterproof flooring option that convincingly replicates wood or stone. Popular in bathrooms as a warmer, softer alternative to tiles.

A toilet with a built-in pump and blade system that grinds waste, allowing installation where gravity drainage isn't possible. Requires electricity and regular maintenance.

The lowest water pressure at which a shower valve or pump will function correctly. Critical when choosing products for gravity-fed or low-pressure systems.

A flexible gap filled with silicone (not grout) that allows for expansion and contraction. Required at wall-to-floor junctions and in large tiled areas.

A valve that prevents water flowing backwards, protecting the plumbing system from contamination. Required in certain installations to meet water regulations.

A rectangular variation of the quadrant enclosure with different length and width dimensions, offering more showering space while maintaining the curved door.

A timer that keeps an extractor fan running for a set period after the light is switched off, ensuring adequate moisture extraction.

A curved pipe section that holds water to prevent drain odours entering the room. Named for its P-shape when viewed from the side.

UK building regulations covering electrical work in bathrooms. Certain work must be certified by a registered electrician or inspected by Building Control.

A type of ceramic tile fired at higher temperatures, making it denser and more water-resistant. Preferred for bathroom floors and wet areas over standard ceramic.

A ceiling-mounted switch operated by a cord, traditionally required for bathroom lights. Modern regs allow wall switches outside Zone 2.

Physical Vapour Deposition—a premium coating process for taps and fittings. More durable than electroplating, resisting tarnishing, scratching, and daily wear.

A curved shower enclosure designed to fit in a corner, with a quarter-circle footprint. Space-efficient for smaller bathrooms.

Slip resistance rating for floor tiles, ranging from R9 (lowest grip) to R13 (highest grip). R10 or higher recommended for bathroom floors.

Residual Current Device—a safety device required for bathroom circuits that cuts power if it detects a fault, preventing electric shock.

Tiles machine-cut to precise dimensions after firing, allowing for narrow grout lines (2-3mm) and a more contemporary, seamless appearance.

A toilet bowl design without a traditional rim. Easier to clean and more hygienic as bacteria cannot accumulate under a hidden rim edge.

Silicone sealant formulated with anti-fungal properties for bathroom use. Quality products resist mould for many years when applied to clean, dry surfaces.

The final installation work after walls and floors are finished. Includes fitting sanitaryware, taps, radiators, and accessories.

A small isolation valve fitted to supply pipes, allowing water to be shut off to individual fixtures without affecting the whole system.

The vertical space required beneath a shower tray for the waste trap and pipework. Low-profile trays need shallower traps (typically 50-90mm).

A cistern fill valve designed to minimise noise during refilling. Particularly valued in open-plan living or bedroom ensuites.

Silicone is flexible and waterproof, used at junctions and corners. Grout is rigid and used between tiles on flat surfaces. Using grout where silicone is needed causes cracking.

A waste fitting with overflow slots, designed for basins and baths that have a built-in overflow. The slots allow overflow water to drain away.

The main vertical drain carrying waste from toilets. Larger diameter (typically 110mm) than waste pipes and vents above roof level.

The main vertical drain pipe that carries waste from toilets down through the building. Also called the soil vent pipe (SVP).

A composite material used for premium shower trays. Made from crusite stone and resin, providing superior strength, warmth underfoot, and durability compared to acrylic.

The structural floor beneath tiles or flooring. May need levelling, strengthening, or replacing before new bathroom flooring can be installed.

Waterproofing a surface (walls and floors) to prevent water penetration. Essential in wet areas like showers and wet rooms to protect the building structure.

A complete waterproofing system typically including membrane, tape, corners, and sealant. Applied to walls and floors before tiling in wet areas.

The internal component of a thermostatic shower valve that regulates temperature. Contains a wax or liquid element that responds to temperature changes.

A shower or tap valve that automatically maintains a constant temperature, even when water pressure fluctuates. Includes safety stops to prevent scalding.

Rigid, waterproof boards used instead of plasterboard in wet areas. Provides a stable, moisture-resistant surface for tiling in showers and around baths.

Thermostatic Mixing Valve Type 2 certification for domestic hot water temperature control. Ensures valves maintain safe temperatures and prevent scalding in domestic settings.

Thermostatic Mixing Valve Type 3 certification for healthcare and high-risk environments. The highest standard for temperature control, required in care homes and hospitals.

The depth of water retained in a trap to block sewer gases. UK regulations require a minimum 50mm seal depth for most bathroom applications.

Natural brass without protective coating that develops a patina over time. Appeals to those who prefer a lived-in, heritage aesthetic.

A waste fitting without overflow slots, used where the basin or bath has no overflow or uses a separate overflow system.

A pressurised hot water cylinder fed directly from the mains. Provides excellent pressure but requires annual servicing by a qualified engineer.

Value Added Tax—currently 20% in the UK. Always confirm whether quotes include VAT, particularly if the installer is VAT registered.

Fixtures mounted on the wall without floor contact, such as toilets and basins. Creates a modern look and allows easier floor cleaning beneath.

The pipe or hole through which water drains from a sink, bath, or shower. Position and size affect product compatibility and installation options.

Smaller diameter pipes (32-40mm) carrying water from basins, baths, and showers. Connects to the soil stack or external drainage.

A common misconception—standard grout is not waterproof, only water-resistant. True waterproofing requires a tanking system beneath the tiles, not the grout alone.

A pre-formed, sloped tray designed for wet room installations. Creates the fall towards the drain and provides a guaranteed waterproof base.

Water Regulations Advisory Scheme certification confirming a product meets UK water regulations. Required for taps, valves, and fittings in new installations.

Electrical safety zones in bathrooms defining what equipment can be installed where. Based on proximity to water sources and splash areas.