25-year plan to ‘replumb’ Merseyside sewers

United Utilities has 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, but it is also what our customers expect and it’s the right thing to do.”

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.

In Merseyside, there will be improvements to 20 storm overflows representing an investment of £166m.  It will involve projects like the one currently underway at Runcorn Wastewater Treatment Works where £4.1m is being invested to boost the site’s storage capacity, reducing the frequency of storm water releases into the River Mersey. 

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 view the Storm Overflow Reduction Plan dashboard, visit https://www.unitedutilities.com/better-rivers/

Image: United Utilities

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