Cleaning our water mains
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 are 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 are carrying out a major programme of work to clean our trunk water mains and local distribution mains.
Find out where we are 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.

- Trunk mains
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
- Local distribution mains
Local distribution mains are the pipes that supply water from trunk mains to customer’s homes. Customer supply pipes are connected to these local distribution mains. These pipes typically range in size from 63mm diameter (2”) to 175mm (9”) in diameter.
We clean these distribution mains by means of a systematic flushing programme.
Understand more about how we clean the water mains by mains flushing