On this page you can find out more about how our mains replacement works may affect you.

During our work

We may need to temporarily turn off your water supply while we are carrying out work.

If your will be without water for more than four hours, we will write to tell you at least 48 hours before we turn the water off.

We will tell you in person or put a notice through your letter box if your water will be turned off for less than four hours.

While your water supply is turned off, please do not use any household appliances such as washing machines, which rely on a constant supply of water, or use water straight from the mains supply.

Central heating systems that have been correctly installed should not be affected by the mains water supply being turned off for short periods.

In some areas, we may arrange with the local authorities and police to suspend parking, to make sure we can do our work quickly and safely.

After our work

Before using your tap water again, please run the cold kitchen tap for around five minutes until the water runs clear.

If your water does not come back on, ask your neighbours whether their supply is back on and check that your inside stop valve is fully open by turning it off and then on again.

• Watch our short video on how to find and use your inside stop valve 

If you need to contact us

If you have any questions about our work, please contact our 24-hour Customer Centre on 0845 9200 800 (Textphone: 0845 7200 899).

Please have your Thames Water reference number to hand, which can be found on the letter you should have already received from us.

Do not use your water or any household appliances, such as a dishwasher or washing machine, until the water runs clear.

Electrical earthing

When we replace the water mains in your area, we will replace the underground metal pipes in your street with plastic pipes. This may affect the electrical earthing for your property.

Until 1967, it was common to earth a property's electrical system to the nearest incoming water pipe, as in those days water pipes were made from metal.

Since then, because of the increasing use of plastic pipes, any new electrical installation must not use the water pipes as the only means of earthing.

It can be dangerous to use metal pipes as the only way of earthing an electrical system.

If your electrical system relies on a water pipe to provide an earth, you or your landlord should get an electrician to check your electrical system and, if necessary, provide a separate earth connection.

For your own peace of mind, before we carry out our work, you should have the electrical installation checked to ensure you have a suitable earth.

Neither we nor our contractors are qualified to advise you, but your electricity company, or a qualified electrician, will be able to help.

Other related advice

Dedicated fire supplies

Some properties have special water supplies for fire-fighting purposes. These properties are usually large offices or industrial buildings that need extra protection.

The owner of the property is responsible for the fire main up to the point where it is connected to our water pipe network.

Some properties have an old fire supply that is no longer in use but is still connected to our water pipe network, and the owner of the property is responsible for any bursts and repairs on this pipe.

If you tell us about a fire main that is no longer used, we will disconnect it during our mains replacement programme.

If you have a fire main, please contact us on 0845 9200 800 (Textphone: 0845 7200 899) to let us know the best time to transfer the supply to the new water main, and to check that this does not reduce the amount of water supplied to your property.

You should also check your buildings insurance.