Replacing old water pipes, from lead to plastic

According to the Drinking Water Inspectorate, lead pipework was commonly used to connect older homes to the water main. Many older homes that have not been modernised still have lead underground or inside. Unpainted lead pipe is dull grey, often with a swollen joint near the stop tap, and shows shiny metal if gently scratched. More lead dissolves into water that stands in the pipe, and in soft water areas.

Your water company can test the water at the kitchen tap if you suspect lead. The pipe from the main in the street to the outside stop valve belongs to the water company; the supply pipe from there into the house, and all the plumbing inside, belongs to the owner. Tell the water company when you plan to replace your part: it is legally required to replace its communication pipe if that is lead and at risk of adding lead to your water. Some companies also help with the cost of the owner's part.

Lead can also come from lead-based solder on copper pipe, which must not be used on drinking water pipework, and from older brass fittings. A plumber replacing lead pipe should check for these too.

Galvanised steel pipe, found in some older houses and flats, corrodes from the inside. The bore narrows, pressure falls and rust appears in the water. It is normally replaced rather than repaired. Copper pipe lasts well, but joints and old repairs fail, and pinhole leaks can appear where water chemistry or installation faults attack it. Modern plastic pipe is quick to install and does not corrode, but it has to be supported properly and kept away from heat sources.

Replacing metal pipes with plastic can remove the path that used to connect some metalwork to earth. After repiping, an electrician should check the main protective bonding to the incoming water pipe.

The external supply pipe usually runs under a front garden or drive to the outside stop tap. It can be replaced by digging a trench or, with less disruption, by pulling a new pipe through a hole bored under the ground. Which method suits depends on the distance, the surface, other services in the ground and whether the old pipe runs in a straight line.

Some terraced streets have shared supply pipes that feed several houses. Replacing a shared pipe for one house often means giving that house its own new supply, which involves the water company and sometimes the neighbours. The plumber should ask the water company how it wants this handled before quoting a fixed price.

Pipe replacement usually means water supply pipes, but owners often ask about drains at the same time. In England and Wales, private sewers that serve more than one property, and lateral drains that run beyond a property's boundary, were transferred to the water and sewerage companies from 1 October 2011. A drain within your boundary that serves only your property is normally still yours. A drainage company can survey old or broken drains with a camera.

Source: gov.uk

• which pipes are replaced: supply pipe, rising main, hot and cold distribution, or all of them
• pipe material and how runs will be supported, insulated and hidden
• trenching or boring outside, and reinstatement of the surface
• contact with the water company about the communication pipe and any shared supply
• how long the water is off and whether a temporary supply is needed
• floorboards, boxing in and making good inside
• a check of main bonding by an electrician afterwards

Describe the pipes, the house and any test result, and confirm your mobile number and email. Plumbers in your area see the job with no name or contact details attached. It is sold once and then removed. The plumber pays for it, not you, and before it receives your details we email you its name, address and phone number.

We cannot guarantee that a plumber buys the job; after 21 days without a buyer it is withdrawn. You remain free to get quotes elsewhere. Offrano checks only that buyers are registered businesses; the DWI advises using a qualified plumber, for example one accredited through an approved contractor scheme such as WaterSafe.