Serving parts of North West London and the Home Counties.

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.

To find out where we are working click here

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.


1. 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.

 

Cleaning pipes by Ice pigging

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

Ice pigging involves isolating a relatively short section of pipe by turning off valves at each end. Water is then displaced to make room for ice solution to be injected. Once the ice solution is in place a valve is then re-opened. This then helps to compact and drive the ice through the pipe, removing any sediment as it goes. The ice is then flushed safely from the main and the water is sampled before the main is returned into supply.

This cleaning method offers a huge benefit to our customer’s in that it involves less excavations and causes less traffic disruption than traditional cleaning techniques. A further benefit is that the majority of this work will be carried out during the night which significantly reduces all forms of disruption to homes, commuters and businesses.

 

The Ice pigging process

To learn more about the process watch a short video below

 

What happens on the day

 

1. The two large articulated vehicles contain the Ice solution (think very large Slush puppy) that is pumped into an isolated section of main via the blue hoses that run from the vehicles to a hydrant stand post.

2. The Ice solution (10m³ to 25m³) is injected via the hydrant stand post into the isolated section of main. During the injection phase the mains pressure is continually monitored to ensure there are no bursts as a result of this activity.

Once all the Ice solution is pumped into the main, an upstream valve is opened, allowing the upstream pressure to push the Ice all the way to its exit point – up 1600m away.

 

3. The Ice exit point is carefully and continually monitored to ensure the procedure is completed successfully.

 

4. The Ice flushing process is designed specifically to remove any of the harmless sediment from the water main that may have accumulated over many years of service. This sediment is diverted into large tankers so it can be disposed of in the most environmentally friendly way.

 

5. When the sediment has been removed, the main is flushed for a further calculated period of time to ensure it continues to meet with our stringent water quality standards before it is returned to service.

 

Frequently Asked Questions

Will my water supply be affected during cleaning works

Occasionally customers may receive discoloured water as a result of cleaning activities. Affinity Water will be constantly monitoring the local network to reduce the impact that discolouration may have.

What should I do if my water supply is discoloured as a result of this work?

Discoloured water is not harmful to health. You should run the first mains-fed tap in your house at a normal rate for up to 30 minutes. Metered customers who experience discoloured water as a result of this work should ring our customer centre on 0800 521 660, as you may be given an allowance on your bill.

Will it be safe to use appliances like my washing machine and dishwasher if my water is discoloured?

Washing machines and dishwashers should only be used if your water supply is running clear.

Will I be notified if my water supply is to be turned off?

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

What do I do if someone needs special assistance, for example, a water supply is needed medical or nursing purposes?

Please have a database of customers who have specific water requirements, if you are concerned please contact us on 0800 521 660, and we will make arrangements to help you.

Will My Water Pressure be Affected

We aim to carry out the majority of work during the night to reduce impact to customer, during cleaning works some customers ay experience changes to the pressure at their taps. If your supply is to be interrupted you will be given 48 hours notice.

Will my Water Quality be affected

Some customer may notice a slight change to the taste or odour following cleaning works, in the extremely unlikely event that you should experience a change in the quality of your water, please contact us on 0800 521 660.

 



2. 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.

 

Cleaning pipes by flushing

We clean these distribution mains by means of a systematic flushing programme. This most commonly involves opening fire hydrants and washouts on our pipe work in a planned sequence to flush out any accumulated sediment.

The majority of this work will be carried out during the night. The work will involve opening fire hydrants and washouts on our pipe work in a planned sequence to safely flush out any accumulated sediment. You may notice personnel on the street carrying out this work and we may cordon off our apparatus in advance of flushing works. We shall notify you by letter before we are due to carry out flushing work in your local area, and all our employees carry company identification and welcome your enquiries.

 

Frequently Asked Questions

How will you know when we are flushing in my area?

Before the flushing starts, you will receive a letter through the post with information about the flushing and the dates when you might be affected.

The vast majority of customers are only affected for part of a single day, but the exact details of your flush will be on the letter.

Will my water supply be affected during cleaning works

Most individual customers are only directly affected for a few hours each as we flush past their property, although we may need to do this on more than one day when working in an area.

Occasionally customers may receive discoloured water as a result of cleaning activities. Affinity Water will be constantly monitoring the local network to reduce the impact that discolouration may have.

What should I do if my water supply is discoloured as a result of this work?

Discoloured water is not harmful to health. You should run the first mains-fed tap in your house at a normal rate for up to 30 minutes. Metered customers who experience discoloured water as a result of this work should ring our customer centre on 0800 521 660, as you may be given an allowance on your bill.

Will it be safe to use appliances like my washing machine and dishwasher if my water is discoloured?

Washing machines and dishwashers should only be used if your water supply is running clear.

Will I be notified if my water supply is to be turned off?

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

What do I do if someone needs special assistance, for example, a water supply is needed medical or nursing purposes?

We have a database of customers who have specific water requirements, if you are concerned please contact us on 0800 521 660, and we will make arrangements to help you.

Will My Water Pressure be Affected

We aim to carry out the majority of work during the night to reduce impact to customer, during cleaning works some customers may experience changes to the pressure at their taps. If your supply is to be interrupted you will be given 48 hours notice.

Will my Water Quality be affected

Some customer may notice a slight change to the taste or odour following cleaning works, in the extremely unlikely event that you should experience a change in the quality of your water, please contact us on 0800 521 660.

How much water is used?

We are committed to using the least amount of water possible during any planned flushing programme. Our flushing plan includes calculations for 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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