What’s Changed at One of Cornwall’s Worst Overflow Sites? Shocking 55% Drop Revealed

Big Drop in Spills at North Petherwin

Storm overflow spills at one of Cornwall’s highest spilling sites have been slashed by more than half, South West Water has confirmed.

The North Petherwin Wastewater Treatment Works, near Launceston, recorded 183 spills in 2023. But targeted improvements carried out in 2024 saw that number fall by 55%.

South West Water said the changes are part of a wider effort to cut the environmental impact of storm overflows across the region.

New Storm Tank Tackles Heavy Rainfall

A new storm tank was installed to manage excess flows during periods of heavy rainfall. When the treatment works reaches full capacity, the tank provides temporary storage for the overflow.

Backed by a pump system with smart controls, the excess water is held on site and automatically returned to the treatment process when there is more capacity. This helps to prevent untreated stormwater from entering the environment.

The tank is also fitted with a mechanical screen to remove debris and a flushing system to keep it clean and effective long term.

📷North Petherwin Storm Tank

More Improvements on the Way

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

“Every person who works for South West Water is passionate about having a positive impact on the local environments that we call home. That’s why it’s so rewarding to see the difference that improvements like these are having to reduce storm overflow spills in the local area.

“There is more work to be done here and across the wider South West and we’re working hard to deliver more great results like this one.”

South West Water said similar upgrades are being rolled out across the region, as it works towards becoming the first water company to achieve fewer than 10 spills per overflow, per year by 2040 — a decade ahead of the government’s target.

📷Karl Stone North Petherwin