Revealed: Major Drop in Storm Overflows at Cornwall Treatment Works After Key Upgrades

South West Water has slashed storm overflow spills by 40% at a wastewater treatment works in Cornwall that was previously one of the region’s biggest polluters.

Targeted improvements at Beals Mill

Beals Mill Wastewater Treatment Works, located near Launceston, had three local storm overflows and recorded a total of 450 spills across them in 2023. One of these overflows ranked among the region’s biggest spillers last year.

However, following targeted improvements, South West Water has seen a dramatic reduction in spills during 2024, despite the wettest hydrological year on record.

The company closed two of the overflows and diverted their flows directly to the treatment works. These upgrades were complemented by the installation of a new screening plant and a storm tank capable of storing up to 40,000 litres of wastewater—the equivalent of about 133 full bathtubs—to manage heavy rainfall.

Tackling groundwater infiltration

Groundwater had also been entering the sewers and flowing into the treatment works. To tackle this, improvements were made to the local pumping station, and work is planned to repair and reline nearby sewers. These efforts aim to prevent groundwater from entering the network and further reduce spills.

Karl Stone, South West Water’s Area Operations Manager for East Cornwall, said:

“It’s rewarding to see real improvements taking shape. At Beals Mill, the upgrades we’ve delivered, including new infrastructure and a better understanding of how groundwater was affecting the site, have already led to a dramatic drop in spills. Our teams live and work in these areas, so we’re personally invested in getting it right. There’s more to do, but we’re committed to keeping up the momentum and making a lasting difference.”

Aiming for regional improvements

Teams are now working to roll out similar solutions across the region. South West Water is aiming to become the first water company to meet the government’s target of achieving less than 10 spills per overflow, per year, by 2040.

📷Karl Stone - Beals Mill