United Utilities in £19bn plan to re-plumb region’s sewers

The water supplier is aiming to make sure all storm overflows in the North West meet new environmental standards by 2050.

A reduction plan is in place meet the requirements of the Environment Act 2021, reducing sewer pollution entering waterways.

Work has started at some high priority sites to improve more than 430 storm overflows.

The first phase of the plan will take place up to 2030, involving £3bn of improvements at 437 sites across the North West.

Schemes which have been completed at sites around the region include:

• Cargo in Cumbria, where temporary treatment and storage facilities have been installed, to be replaced by a permanent system,
• Southwaite wastewater treatment works near Carlisle. The site has been upgraded and a wetland created to clean the storm water before entering the River Eden.
• Atherton, Wigan, where a storm storage tank has been built beneath Vulcan Park. The £5m scheme reduces storm spills into Collier Brook and the River Glaze.
• Nelson, Burnley. A storm water storage tank has been built to reduce storm spills into the River Calder.
• Worsley, work is complete on a 500,000 cubic metre storage tank to reduce storm overflows into Astley Brook.

Schemes underway at other sites include:

• Storm storage tanks have been built at Horwich wastewater treatment works and in the nearby sewer network, to improve 38km of the River Douglas.  A wetland is being created at Eccleston to filter and clean storm water before being returned to Syd Brook, a tributary of the River Yarrow.
• Sunny Bank Road, Bury. A £2.5m project began in October 2023 to install an underground storage tank. The tank holds 500,000 litres and will reduce how often the storm overflow operates during periods of heavy rain, improving water quality in Parr Brook and River Roch.
• Ambleside, Elterwater, Near Sawrey and Hawkshead near Windermere, where a £41m project will involve the construction of storm water storage. Redundant tanks are being repurposed, and natural soakaway solutions created to reduce the volume of rain entering the sewer network.
• Bolton, £38m is being spent to reduce the amount of times that storm overflows operate in heavy rain from sites in Astley Bridge, Dunscar Bridge and Firwood industrial estate.
• Nuttall Park, Ramsbottom. Construction has started on an underground storm water storage tank that will be capable of holding up to 3.5m litres of water.

Since December 2023 all sites are monitored, with work being prioritised at locations which operate most frequently, or discharge into bathing waters and environmentally sensitive locations.

Jo Harrison, asset management director at United Utilities, said: “The multi-billion pound programme we are now embarking upon will see the biggest overhaul of the region’s sewer network in a century.

“Not only is this now enshrined in law, it is what our customers expect and it’s the right thing to do.”

Harrison added: “We are making a fundamental change to the way our sewer system has been designed, and change on this scale cannot happen overnight.

“We are re-plumbing our drainage systems, building storage tanks to increase the capacity, separating rainwater out of sewers, and harnessing the power of nature to treat storm water before it is returned to the environment.

“Work has already started and people are going to see much more of this over the next 25 years.”