Efforts to prevent untreated wastewater reaching the River Avon running through Bath are being enhanced with a second project to reduce storm overflow operation in the city.

More than £650,000 is being invested on storage capacity in the Fox Hill area, which should dramatically reduce the issue of heavy storms overwhelming the sewer system and causing overflows to operate automatically, releasing diluted water before it is treated.

The three-month scheme is one of nearly 100 being completed under Wessex Water’s £3 million a month programme before 2025 to reduce the overall operation of overflows by a quarter, while boosting support for the environment.

Teams will move on to the site just north of Combe Down in June to build the new tank which will be capable of hosting nearly 100,000 litres of excess water. A length of new sewer and new manholes will also be constructed as part of the project.

During periods of heavy rain, excess flows from combined sewers carrying both foul water from home and businesses and rain run-off will be held in the tank to prevent overflows from operating at the River Avon more than a kilometre away.

Instead, the stormwater will be returned to the sewer once the weather has eased and piped onwards to a water recycling centre for treatment and safe return to the environment.

Wessex Water’s project manager, Greg Andrews, said, “While overflows have always been a part of this country’s sewerage system protecting homes and businesses from flooding if the network become overwhelmed, we’re committed to progressively reducing their use and eliminating the release of untreated wastewater.

“Between now and 2025 we’re tackling the overflows in our region that have operated most frequently in the past and our work at Fox Hill is one of those 13 priority projects.

“Holding back excess water for safe treatment is one way we can help ease the pressure excess rainfall can cause on the sewer system and protect the health of the River Avon.’’

The scheme will take place on public land, with one short diversion to a local public right of way while work is in progress.

It will be the second such scheme to protect the river to take place in Bath in the last eight months, after more than £1.3 million was spent in the autumn to install a storm tank in the car park of Bath RFC’s playing fields off London Road in the east of the city.

Capable of holding more than 170,000 litres of storm water, the Lambridge tank was followed by two further projects to enhance protection of the Avon, with a further 160,000 litres of storage space being created within Victory Field, in Bradford on Avon as part of a near-£2 million investment that was completed this month.

More than £800,000 is also being invested to build a below-ground tank that can hold 50,000 litres of water in Hanham in the east of Bristol this winter.

Storage is just one way Wessex Water is tackling storm overflows before 2025, with increased capacity to treat sewage at 42 of its water recycling centres, including introducing more nature-based and low-carbon treatment methods such as reedbeds and wetlands also being delivered.

Investigation and monitoring of overflows has also been enhanced, along with increased sewer relining to help keep wastewater within the system and prevent infiltration of groundwater that can lead to flooding.

The company has also unveiled proposals to invest a record £400 million towards the goal of reducing overflow operation in its next five-year investment period between 2025 and 2030, subject to approval by industry regulators.