Falmouth Stormwater Overflow Improvement Scheme

We're working fast to reduce spills in Falmouth

Falmouth's beach at Gyllyngvase has enjoyed Good bathing water for many years now. 

But we know that sometimes the sewer system is struggling to cope. Our investigations tell us that this is for a number of reasons including population growth in the area, groundwater entering the sewers, and the age of some of our assets.

We're on a mission to reduce the impact the town's sewerage system is having on the environment, including in the estuary waters.

Queen Mary Gardens Programme

The Queen Mary Gardens Programme forms a key part of South West Water’s wider Falmouth Stormwater Overflow Improvement Scheme. This initiative aims to reduce the environmental impact of storm overflows in Falmouth by tackling infiltration, increasing stormwater storage, separating surface and foul water flows, and upgrading treatment capacity.

This scheme is part of South West Water’s ambitious Turning the Tide programme that will invest record amounts to target storm overflows throughout the region.

Project details

We’re building a new stormwater tank in Queen Mary Gardens that will hold 302,000 litres of water. This will mean more wastewater can be stored at times of heavy rainfall then treated, reducing our reliance on storm overflows in Falmouth.

The tank will be installed via the Queen Mary Gardens/Gyllyngvase car park, with all flows screened before entering. These screens are also being upgraded.

Gyllyngvase car park will be closed from October 2025 until the project is complete (expected around March 2026), we apologise for any inconvenience.

Programme of works

Date Activity
Monday 6 October   Start on site  
April 2026   Planned completion and reinstatement  
Picture of works to separate sewers
What we're tackling
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Combined sewers.

Combined sewers carry both foul sewage from homes and businesses and rainwater from roofs, paved areas and in some areas, run off from roads to the treatment works. Rainwater itself doesn’t need treatment before being released back into rivers, but where it enters a combined sewer network it uses valuable capacity and adds pressure to our pumps and storm tanks.

The best way to reduce this pressure is to separate foul and surface water flows. By building one sewer for foul sewage and another for rainwater, we can keep clean water out of the treatment process and release it safely back into rivers after passing through an oil interceptor. Customers can also play a big part by keeping rainwater out of combined sewers, for example through soakaways or other drainage solutions. Checking how your roof and driveway runoff is connected can make a difference. If none of your surface water drains to the public sewer, you may qualify for a lower bill and help ease pressure on the system during wet weather.

Image of a sewer culvert after it has been lined
What we're tackling
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2. Infiltration

Infiltration is when surface water or groundwater enters our sewers in places it's not meant to (e.g. through manhole covers).

This means that a lot more wastewater enters the sewers and increases the risk of activating our storm overflows.

To stop infiltration we'll be lining, repairing and replacing our pipes and manhole covers in hotspot areas. We call this rehabilitation work.

Picture of a storm tank
What we're tackling
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3. Storm storage

Storm water is the number one cause of storm overflows. The huge rainfalls we're experiencing as climate change takes hold are overwhelming our sewers, meaning our storm tanks fill up faster and start overflowing before our pumps have chance to reduce the volume inside them.

We're hoping that our work to reduce infiltration will help reduce the amount of storm water entering our sewers.

But, we're also making sure there's enough storage to hold it all. That's why we're looking into building brand new storm storage near Queen Mary Gardens and The Moor, and we're investigating other potential areas.

Waste water treatment centre
What we're tackling
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4. Our treatment works

By upgrading our treatment works we can reduce the amount of time wastewater stays in our system. We're looking into ways to increase the volume of wastewater that can be treated at any time. A solution will be designed based on the results of our investigations.