Plain-English meanings for the plumbing and water-regulation standards used across the questions.
The plumbing questions use these short names. Here is what each one means.
- Approved Document G — guidance in England on sanitation, hot water safety and water efficiency.
- Approved Document H — drainage and waste disposal (above- and below-ground).
- Approved Document L — conservation of fuel and power, including heating controls and efficiency.
- Approved Document P — electrical safety in dwellings.
- Water Fittings Regulations 1999 — the England and Wales rules addressing waste, misuse, undue consumption and contamination of supplied water. Northern Ireland has its 2009 regulations; Scotland uses the 2014 Water Fittings Byelaws.
- WRAS / Water Regs UK — WRAS operates a water-fittings and materials approval scheme; Water Regs UK publishes regulations guidance and supports water-company work. Product approval and correct installation are different checks.
- Fluid categories 1–5 — the backflow risk scale: category 1 is wholesome water, category 5 is a serious health hazard. The higher the category, the stronger the backflow protection required.
- G3 — the hot-water supply and safety requirement within Part G. It covers relevant hot-water systems, including vented and unvented storage; it is not solely the name for an unvented cylinder.
- TMV — thermostatic mixing valve: blends hot and cold water to control outlet temperature and reduce scalding risk. Its suitability, setting and maintenance still matter.
- Level 2 / Level 3 — the core vocational plumbing and domestic-heating qualification stages.
- CSCS — Construction Skills Certification Scheme. CSCS and allied occupation cards can evidence the qualifications or training required for that card; the contractor sets site-entry policy.
Use the guidance for the applicable UK nation, building and work. Approved Documents explain ways of meeting Building Regulations requirements; the document, the legal requirement and a product approval are not interchangeable.