Southern Water is nearing the end of a £25m project that aims to help protect and enhance Southampton Water.

Improvements to the Millbrook Wastewater Treatment Works form part of a wider £63m scheme to safeguard shellfish in the area.

It follows widespread anger over the amount of raw sewage discharged into UK rivers and coastal waters during heavy rain.

The Millbrook project has already doubled the site's stormwater storage capacity. The facility has also been equipped with a new ultraviolet treatment process to improve water quality.

The final phase of work, now underway, will increase the site’s treatment capacity by adding new tanks, technology, and pipework.

Daily Echo: The Millbrook Wastewater Treatment Works is being given a £25m upgrade by Southern WaterThe Millbrook Wastewater Treatment Works is being given a £25m upgrade by Southern Water (Image: Southern Water)

Southern Water says the improvements will help reduce the frequency of storm overflows.

The company is also upgrading other wastewater treatment works in the Solent area, with £8m being spent at Ashlett Creek, near Fawley, £13m at Woolston, and £18m at Slowhill Copse in Marchwood.

READ MORE: Work about to start on £8m scheme to improve Fawley wastewater treatment plant

Wastewater operations director John Penicud said Southern Water recognised the importance of playing its part in protecting the environment.

He added: "All these projects will play a crucial role in protecting shellfish and improving the health of Southampton Water in the coming years.”

The work is being carried out by GTb, a joint venture between Galliford Try Environment and Binnies UK.

Daily Echo: The Ashlett Creek Wastewater Treatment Works is also being upgradedThe Ashlett Creek Wastewater Treatment Works is also being upgraded (Image: Southern Water)

Kennith Loftus, project design lead for GTb, said: “Once all this work is finished, the quantity of sewage treated and the quality of the final effluent will be significantly improved. This will help protect the important shellfish and other marine habitats in and around Southampton.”

On an average day, Southern Water supplies 556 million litres of water and treats 13,371 million litres of wastewater.

A company spokesperson said: “We invest to serve our customers, protect the environment and boost regional economies. Between 2020 and 2025 we are injecting £3 billion into improving our performance."

READ MORE: Shareholders inject a further £550m into Southern Water to help company shore up its finances

Most of the UK has a combined sewerage system, which means rainwater and wastewater are transported to sewage treatment works in the same pipes.

Water bosses are allowed to use storm overflows only in exceptional circumstances, such as heavy rain, to prevent the system from being overloaded.

But recent figures show sewage was released into England's waterways more than 300,000 times last year.

In 2021 Southern Water was fined a record £90m for dumping sewage into rivers and coastal waters in Hampshire and other parts of the south coast between 2010 and 2015.