Sidmouth Sewer Improvement Schemes
Increasing storm storage in Sidmouth
What we're doing
Starting in December 2025 South West Water will be installing a new storm storage tank in The Ham, once complete the new tank will provide 100,000 litres of storm water storage.
This will help to reduce storm overflow spills from The Ham Pumping Station and safeguard water quality at Sidmouth Town Beach, which has consistently received “Excellent” bathing water status.
To allow the work to take place safely, The Ham will be closed for recreational use from December 2025 until the works are completed, which is expected to be around June 2026.
Works already completed
This work follows work carried out in 2024 to reduce groundwater entering the sewers. The company’s dedicated teams surveyed 8,475 metres of sewer and relined 604 metres of sewer.
Further sewer improvement works will take place once the storm storage tank is installed. These works will likely take place in The Hams car park and upstream in the catchment.
1. 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.
2. 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 a brand new storm tank near The Ham.
3. Combined sewers
Combined sewers take both foul sewage from homes and businesses, as well as surface water from roads, to the treatment works.
Being rainwater, surface water doesn't need much treatment before being released back into rivers. Sending it to the treatment works not only wastes energy and money in transporting and treating it, but also risks overloading our pump stations and storm tanks.
By seperating sewers (building one to hold the foul flows and one to hold surface water) we can reduce the flows inside our sewers and reduce the risk of storm overflows. The surface water is released into rivers after going through an oil interceptor.
4. Our storm overflows
Following extensive investigations, the work we're doing in this scheme is expected to significantly reduce our reliance on the storm overflows in Sidmouth.
But, they will still play an important role in internal flood-prevention. That's why we're investing in their maintenance - upgrading their screens and relocating our monitoring chambers.
This work will help reduce the impact of overflows on the environment, and allow us to better monitor, check and maintain the overflows.