25-year plan in the pipeline to ‘’re-plumb’ North West sewers

  • £multi-billion investment will continue up to 2050
  • Dashboard published with plan for every storm overflow
  • 437 storm overflows will be improved by 2030 – reducing spills by at least 50%

United Utilities has today published a road map showing how it will deliver cleaner rivers, beaches and lakes across the North West – the biggest investment of its kind in the UK.

By 2050 the goal is to ensure that storm overflows, the relief points that prevent sewers from backing up and flooding homes and businesses in heavy rain, each operate less than 10 times a year.

The Storm Overflow Reduction Plan, expected to cost some £19 billion in the North West region alone, will meet the new requirements of the Environment Act 2021, bringing a massive reduction in sewer pollution entering the region’s waterways.  Work has already started at some of the highest priority sites and by 2030 more than 430 storm overflows will be improved.

Jo Harrison, Asset Management Director at United Utilities, said:  “At United Utilities, our purpose is very clear – we don’t just supply water, we also want to make the North West greener, stronger and healthier.

“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.”

Today a dashboard has been published showing the locations of every storm overflow in the UK, with a timescale for achieving the target of 10 operations a year.  The first phase of the Storm Overflow Reduction Plan will take place up to 2030, and will involve £3 billion of improvements at 437 sites across the North West.

Progress is already being made and schemes have been completed at sites around the region including:

  • Cargo in Cumbria, where temporary treatment and storage facilities have been installed. It will be replaced by a permanent system, but it is already showing results since it came online in August 2023, with the number of spills reduced from 343 a year to just one occasion since then.
  • Southwaite wastewater treatment works near Carlisle, where the whole site has been upgraded and a new wetland created to clean the storm water before it enters the River Eden.
  • Atherton near Wigan, where a storm storage tank has been built beneath Vulcan Park. The £5m scheme is already reducing storm spills into Collier Brook and the River Glaze 
  • Nelson near Burnley, where a storm water storage tank the size of 25,000 bath tubs has been built and is reducing storm spills into the River Calder
  • Worsley, works have now been completed on a 500,000 cubic metre sorage tank to help reduce storm overflows into Astley Brook

Schemes are underway at other sites including:

  • Chorley where new storm storage tanks have been built at Horwich wastewater treatment works and in the nearby sewer network, already helping improve 38km of the River Douglas.  And a new wetland is being created at Eccleston which will filter and clean storm water before being returned to Syd Brook, a tributary of the River Yarrow.  Made up of three adjoining reedbeds, the new wetland will have air piped into the water, increasing its performance by adding oxygen to the process
  • Sunny Bank Road near Bury, where a £2.5m project began in October 2023 to install a new underground storage tank.  The new storm tank holds 500,000 litres and will help to reduce the number of times the storm overflow operates during periods of heavy rainfall, improving water quality in Parr Brook and River Roch
  • Ambleside, Elterwater, Near Sawrey and Hawkshead all near Windermere where a £41m project will involve the construction of new storm water storage, redundant tanks are being repurposed, and natural soakaway solutions will be created to reduce the volume of rainfall entering the sewer network
  • Bolton, £38 million to reduce the amount of times that storm overflows operate in heavy rainfall from sites in Astley Bridge, Dunscar Bridge and Firwood industrial estate.
  • Nuttall, Ramsbottom, construction is underway on an underground storm water storage tank that will be capable of holding up to 3.5 million litres of water.

There are more than 2,200 storm overflows within the wastewater system across the North West region. Like the overflow on a bath, these are designed to prevent flooding and provide a route for water to take when sewers fill during heavy rain – automatically releasing a diluted mixture of sewage and rainwater into the environment.

Since December 2023 every one of these sites is now monitored, allowing United Utilities to build a picture of how often each site operates and which should be tackled first.  Improvement work will be prioritised at the sites which operate most frequently or which discharge into bathing waters or environmentally sensitive locations.

Jo 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.”

For further information and to visit the dashboard, visit https://www.unitedutilities.com/better-rivers