South West Water is doing more harm to the environment than any other water company in England, according to new analysis, with more sewage discharged in Devon, Cornwall, Dorset and Somerset than anywhere else.
Friends of the Earth analysed water companies’ environmental performance in six categories: sewage spills, water quality at bathing sites, pollution incidents or warnings at bathing sites, severity of sewage pollution at bathing sites, the percentage of rivers rated below the standard for good ecological health, and the affordability of bills.
South West Water, which operates across Devon, Cornwall and parts of Dorset and Somerset, was among the top three worst performers in four out of the six categories.
The water company had the highest total duration of sewage spill events since 2024, averaging 574,323 hours annually. Severn Trent and Yorkshire Water came second and third respectively but were outstripped by South West Water, by almost 200,000 spill hours.
South West Water’s designated bathing sites also recorded the most pollution incidents and warnings, with 666 recorded in 2025 alone.
There are 157 official bathing sites in South West Water’s catchment. If a site is designated, the Environment Agency will monitor water quality during the bathing season to protect people’s health.
A spokesperson for the company said: “We manage more than a third of England’s designated bathing waters, so improving water quality is a huge priority for us. We’re already seeing progress, with storm overflow spills down 17% and spill duration down 25% over the past year, despite significantly higher rainfall across the region. We’re also on track to meet new Environment Act bathing water standards by 2030, five years ahead of the national deadline, showing the impact of record investment across the south-west.”
Alongside this poor environmental performance, Friends of the Earth said South West Water’s roughly 1.8 million customers faced some of the highest water bills at £726 annually. Since 2024, they have had the second biggest increase in England, with bills rising by 39%.
Southern Water is responsible for the most expensive water bills in England and the biggest increase since 2024, with £281 added to the average bill in that period.
Kierra Box, a water campaigner at Friends of the Earth, is calling on the government to bring forward a robust clean water bill that sets out a “meaningful plan for restoring the health of the UK’s rivers and seas”.
She said: “People have had enough of hearing ministers say they’ll fix the problem, only to bring in measures that superficially address the issue. If we’re to end the sewage scandal once and for all, we must see the government committing to a complete overhaul of our water system.”
A Defra spokesperson said: “It is totally unacceptable that some water companies are failing to deliver value for money for customers and polluting our rivers, lakes and seas.
“The government recognises that we need to build on our reforms which banned bonuses so our water system works for the public. That’s why we are driving forward the biggest overhaul of the water sector in a generation, with new legislation to give the public more control and help keep bills as low as possible.”
Friends of the Earth is also calling on the government to nationalise water companies. Sources recently told the Guardian that the prime minister, Andy Burnham, was considering ripping up insolvency laws to make it easier to bring key utilities such as water companies under public control. However, the Times reported that Burnham had shelved plans to put Thames Water into administration amid concerns about the cost and the legal risk involved.
Defra said Thames Water remained financially stable, but the government stood “ready for all eventualities, including applying for a special administration regime if that were to become necessary”.
A Water UK spokesperson said: “No sewage spill is ever acceptable, and we are working to end them as fast as we physically can. That’s why we are tripling investment over the next five years to halve spills from storm overflows and upgrade the capacity of 1,700 wastewater treatment works.”
