South West Water has reduced storm overflow spills at one of its highest spilling sites in Cornwall after recent improvements in the area.

Investment in the wastewater treatment works in the village of Fraddon, mid-Cornwall, in December 2024 has delivered improvements to the site’s performance so far, cutting storm overflow spills by 40% in January 2025, compared to January 2024.

South West Water said it has achieved this reduction by installing a storm storage tank at Fraddon Treatment Works which holds excess flows during heavy rainfall and reduces the amount of times the storm overflow operates.

Rather than building entirely new infrastructure, South West Water’s team repurposed an existing lagoon into a storm tank to create the necessary storage to significantly reduce the frequency of overflows.

Andy Pettifer, South West Water’s Operations Manager for West Cornwall, said:

“The improvements at Fraddon show how targeted investment can deliver real environmental benefits. By upgrading existing infrastructure and adding new storm storage capacity, we’ve been able to significantly reduce spills in the area.” These improvements are part of a wider investment programme aimed at reducing storm overflows and improving water quality across the South West.

New storage tank and sewer lining cuts spills on Dartmoor

The water company has also finished improvements on Dartmoor as part of its work to reduce the use of storm overflows across the region.

Horrabridge Wastewater Treatment Works, in West Devon, was one of the South West’s highest spilling storm overflows in 2023 but investment from South West Water is already helping to deliver improvements to the site.

South West Water teams carried out investigations and surveyed over 1.5 kilometres of pipework. Which revealed that surface water and groundwater was finding its way into local sewers and putting additional pressure on the treatment works during wet weather.

To prevent this from happening the company installed a protective lining to 880 metres of sewer in the area and carried out repairs across the local network, including upgrades to around 30 manholes.

Alongside this, work was carried out at the treatment works to upgrade the pumps and add a second storage tank to increase the site’s capacity during periods of heavy rainfall. As a result, there has been one spill from the storm overflow at Horrabridge Wastewater Treatment Works since 1 January, compared to 32 spills in the same period last year.

The ongoing improvements across the South West Water region form part of wider plans to become the first water company to meet the government’s target of achieving less than 10 spills per overflow per year – a decade ahead of target.

South West Water is working to become the first water company to meet the government’s target of achieving less than 10 spills per overflow per year – a decade ahead of target.