Lead pipes in London homes: leaks and replacement

London’s housing is old, and so is some of the pipework hidden in it. If your home was built before 1970 and has not been fully replumbed since, there is a chance some of your water pipes are lead. That matters for two reasons. Lead in drinking water is a health concern, and old lead pipework is one of the causes of leaks and bursts common in Victorian and Edwardian homes.

Thames Water says you are unlikely to have lead pipes if your house was built after 1970, or if all your pipework has been replaced since. Before that, it is worth checking.

Why Hackney is a good example

Hackney has thousands of Victorian terraces in Stoke Newington, Clapton, Homerton and De Beauvoir, many now split into flats. In the 2021 Census, 15.5% of Hackney households lived in part of a converted or shared house and 13.9% in terraced houses. These homes were built long before 1970, and many still have an old lead supply pipe coming in from the pavement, even where the rest of the house has been replumbed in copper or plastic.

In a conversion, the lead pipe often feeds the whole building before splitting into a supply for each flat. That makes a leak on it a problem for everyone in the house.

How to spot lead pipe

Check the pipe running into your stop tap, usually under the kitchen sink. Look for these signs.

Sign	Lead	Copper	Plastic
Colour	Dull grey	Orange brown, or green where tarnished	White, grey, blue or black
Scratch test with a coin	Shiny silver	Copper colour	No change
Tap with a metal object	Dull thud	Ringing sound	Dull, soft sound
Joints	Rounded bulge, like a swelling	Neat brass or soldered fittings	Push fit or compression fittings
Bending	Soft, slightly wavy runs	Straight with bends	Flexible

Lead is often hard to see because it goes straight into the floor. If you are not sure, ask a plumber to look when they are next at the property.

Why old lead pipes leak and burst

Lead is soft. Over decades it sags, thins and can crack where it bends. The joints, known as wiped joints, were made by hand with molten solder and can fail with age. The places most common problems are:

• where a lead pipe joins newer copper or plastic, especially if the join was done badly
• where the pipe has been knocked or bent during kitchen or bathroom work
• in cellars and under suspended floors where the pipe freezes in cold weather
• under front gardens, where ground movement strains the pipe

A leaking lead supply pipe under a front garden may never show on the surface. The first sign might be low water pressure, a damp patch in the cellar or a letter from Thames Water about a leak on your property. If that happens, our guide on the Thames Water four week rule explains your obligations.

Thames Water’s lead pipe replacement scheme

Thames Water runs a lead pipe replacement scheme. Its criteria include having a property built before 1970. Check the full criteria on the Thames Water website before arranging any work, because the details of what is covered, and how you apply, are set by Thames Water rather than your plumber.

Remember the general rule from Thames Water’s pipe responsibility page: Thames Water owns the communication pipe up to your boundary, and the supply pipe from the boundary into your home is yours. Internal pipes are yours too. If you share a lead supply pipe with neighbours, as is common in terraced streets, Thames Water says the households served have joint responsibility for it.

If a lead pipe bursts

Treat it like any other burst pipe. Turn off the stop tap clockwise. If the burst is on the lead supply pipe before the stop tap, the inside valve will not help, and you may need the outside stop valve in the pavement. Switch off electrics near the water, open the cold taps to drain the pipes and contain the water.

Do not try to squeeze or bend a lead pipe to stop a leak. It is soft and will split further. A plumber will cut out the damaged section and join new pipe using fittings made for connecting to lead, or replace the pipe back to a sound point. Our burst pipe repair page explains what the visit involves.

Repair or replace

Situation	Usually sensible
One leaking joint on otherwise sound pipe	Cut out and repair that section
Pipe split after frost	Replace the damaged length, check the rest
Old lead supply pipe with low pressure	Consider replacing the supply pipe
Lead internal runs feeding the kitchen tap	Consider replacing, and check the Thames Water scheme

Lead and drinking water

Lead can dissolve into water that sits in lead pipes, especially overnight. If you know you have lead pipes, Thames Water’s lead guidance is the place to start. Replacing the lead supply pipe is the long term fix.

Tenants and leaseholders

If you rent, your landlord is responsible for the water supply installations under section 11 of the Landlord and Tenant Act 1985. Report a leaking lead pipe in writing. If you are a leaseholder in a converted house and the lead supply serves every flat, it is likely a shared or communal pipe, so involve the freeholder and the other leaseholders before any work starts.

Before you start any building work

If you are planning a new kitchen or bathroom in an older Hackney home, ask the plumber to check for lead before the floor goes back down. Old lead runs are easily disturbed by builders, and a pipe that has been fine for decades can start weeping at a joint once it is moved. Replacing a short run while everything is open is usually simpler than coming back to it after a leak has stained the ceiling below.