The main rules that apply to home plumbing in the UK: the water fittings regulations, work you must notify to your water supplier, Building Regulations for drainage and hot water, Gas Safe, lead pipes and your responsibilities for supply pipes.
Many people assume plumbing rules only apply to professionals. In fact, the main regulations apply to the installation itself, whoever does the work. Knowing them helps you avoid contaminating drinking water, causing leaks, or problems when you sell your home. This is general guidance, not legal advice.
The water fittings regulations
In England and Wales, the Water Supply (Water Fittings) Regulations 1999 cover plumbing systems and appliances connected to the public water supply. Scotland has the Scottish Water Byelaws 2004, and Northern Ireland has its own equivalent. They require fittings to be of suitable quality and installed so that they don't cause:
- contamination, for example through backflow from hoses, garden systems or appliances;
- waste of water;
- misuse or undue consumption;
- erroneous measurement of metered water.
Products tested and approved by bodies such as WRAS show they meet the requirements.
Work you must tell your water supplier about
Some installations must be notified to your water supplier before work begins, so they can check compliance. Examples include:
- a bath holding more than 230 litres;
- a bidet with an ascending spray or flexible hose;
- a pump drawing more than 12 litres a minute from the supply;
- a water softener or reverse osmosis unit that produces waste water;
- a garden watering system, other than a hand-held hose;
- a pond or swimming pool holding more than 10,000 litres that fills automatically.
Approved plumbers belonging to a scheme such as WaterSafe can self-certify some work. Check your supplier's website for its notification process.
Backflow protection
Water can be sucked back into the mains if pressure drops. Outside taps need a double check valve, and appliances such as washing machines usually include built-in protection. Higher-risk uses need stronger protection.
Building Regulations
Building Regulations apply to some plumbing and heating work in England and Wales, with separate systems in Scotland and Northern Ireland. Work that commonly needs approval or a registered installer includes:
- new drainage connections and changes to soil and waste pipes (Part H);
- unvented hot water storage systems, which must be installed by a competent person (Part G);
- new or replacement boilers and heating systems (Part L, energy efficiency);
- electrical work in bathrooms (Part P).
Using an installer registered with a competent person scheme means they can self-certify, and you'll get a certificate. Keep it: your buyer's solicitor may ask for it.
Gas work
By law, anyone working on gas appliances or pipework in your home must be on the Gas Safe Register. Landlords must arrange an annual gas safety check. If you smell gas, call 0800 111 999.
Lead pipes
Homes built before about 1970 may still have lead pipes. Lead can dissolve into drinking water, so replacement is recommended. Your water company may offer advice, testing or help with replacing its part of the pipe.
Who is responsible for which pipes?
- The water company is generally responsible for the communication pipe up to your property boundary or the external stop tap.
- You are usually responsible for the supply pipe from the boundary into your home, and all pipework inside.
- For sewers, many shared sewers and lateral drains outside property boundaries transferred to water companies in England and Wales in 2011. Your own drains within your boundary are usually your responsibility.
Frequently asked questions
Can the water company inspect my plumbing?
Yes, water suppliers have powers to inspect and require changes to non-compliant fittings.
Do I need permission to fit a water softener?
You must notify your supplier if it produces waste water, and leave a drinking water tap unsoftened.
Sources and further reading
- WRAS: Water Regulations Advisory Scheme
- legislation.gov.uk: Water Supply (Water Fittings) Regulations 1999
- GOV.UK: Building regulations approval
- Gas Safe Register
- Drinking Water Inspectorate: Lead
Facts checked on 20 October 2026. Spotted an error? Tell us and we will correct it.