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Why do we need to clean the water mains?

The water we provide you is of a very high quality. However, over time, natural sediments may build up in our pipe work. If these are left, you could occasionally experience some discolouration of your water. As part of our routine maintenance programme, we carry out regular activity to flush the water mains to remove these sediments, where this is required.

About our works

We're principally employing a technique called Ice pigging to clean the majority of the trunk main network. Trunk mains supply water from our water treatment works and storage facilities such as our towers and reservoirs, into the local distribution network. Local distribution mains, those pipes that supply water from trunk mains to customer’s homes, will be cleaned by means of a systematic flushing programme.

How we clean the water mains

Over a period of time, harmless sediment can build up on the inside of these trunk mains and can result in customers receiving discoloured water.

To further reduce the likelihood of discoloured water we're carrying out a major programme of work to clean our trunk water mains and local distribution mains.

Find out where we're working

There are two types of water mains; Trunk mains and local distribution mains. Trunk mains supply water from our water sources, reservoirs and towers into the local distribution network. The Local distribution mains supply water to customer’s homes from the Trunk mains.

Water network

Trunk mains

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Trunk mains supply water from our water sources, towers and reservoirs into the local distribution network. These pipes are larger in size than the local water mains. Typically they range is in size from 200mm diameter (8”) to 1m (40”) in diameter.

We are principally employing a technique called Ice pigging to clean the majority of the trunk main network.

Understand more about how we clean the water mains by ice pigging

Cleaning local water mains

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We clean local water mains to remove the natural sediments that can build up over time. By flushing the mains as part of a regular maintenance programme, we can ensure we continue to provide you - and your neighbours, with high quality drinking water for many years to come.


How will this affect me?

To minimise any disruption to you, we carry out this work overnight. We'll let you know before it takes place.

  • As this work is being completed, you may notice your water becomes slightly discoloured or cloudy. This is temporary and your water is still safe to drink. Running your taps for a few minutes will help to clear it.
  • You may experience lower water pressure. To prevent any interruptions to your appliances, we suggest you do not run your washing machines or dishwashers during the time we plan to carry out the work. Your central heating system won't be affected.
  • Some areas in the road and footpaths may be coned off for safety. While we carry out this essential work our teams will be following the latest government guidance, we ask that this is respected for your safety and ours.

Frequently asked questions

If my water supply is discoloured is it safe to use my appliances?

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Washing machines and dishwashers should only be used if your water supply is running clear. This is to prevent any staining.

Will my water pressure be affected?

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Some customers may experience a change in their water pressure, but it will only be temporary. We run our mains cleaning programme at night , between 10pm and 6am to minimise any disruption to you.

How can you help someone who needs special assistance?

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The Priority Services Register (PSR) is free to join. We don't expect you'll be without water, but it helps us to know who may require extra help in the unlikely event that your water supply is interrupted. So if you have additional physical or mental health needs or are registered as Clinically Vulnerable please register here.

Will I be notified if my water supply will be turned off?

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We will notify you of any planned interruptions to your water supply.

How much water is used?

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We are committed to using the least amount of water possible to clean the mains. We calculate the precise volume of water required for each and every section of pipe work. This ensures that we always use the least amount of water possible to achieve correct amount of cleaning.

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