We just know it’s wrong, don’t we? Clean water is vital to human and animal life. To be pumping raw human waste into our natural waterways is unacceptable. It seems obvious to us, but the government’s clearly not on the same page.
Water companies have been releasing sewage into rivers for years, but it worsened when Liz Truss was Minister for the Environment from 2014 to 2016. She oversaw a £24 million cut to the Environment Agency grant for surveillance to stop raw sewage dumping. Spills have at least doubled since.
Surprisingly, it’s often permissible.
Overflowing sewers
England has an antiquated ‘combined’ sewerage system, with rainwater plus bathroom and kitchen wastewater all going in the same pipes to treatment works. During heavy rain, the pipes struggle with the volume. To prevent it backing up into homes or streets, companies are permitted to use release valves, called Combined Sewer Overflows (CSOs), to discharge untreated sewage into waterways. They should only be used exceptionally, ‘during heavy rainfall’.
Sewage without storms
In East Anglia, 2023 so far has been very dry, with barely 20% of normal rainfall. Essex was drier, with 8% of the February average – the lowest in the UK. Historical weather data for Stansted, Essex shows virtually no rain from mid-January to early March. So, during these dry months, storm overflows shouldn’t really have happened, but they have. There is evidence of this, as companies must now have Event Duration Monitors (EDMs) on CSO pipes to monitor discharges into rivers.
Out of date information
The most recent data from Anglian Water, the Rivers Trust and Dept for Environment is from 2021. It shows hundreds of thousands of discharges.
Not much use if you fancy wild swimming in the Stour and want to check if it’s safe.
Sewage discharges: real time data
So far, so historic. But in some areas, it’s now possible to see discharges as they are occurring, so you know whether to take a dip. You can also look at weather data to check if a storm might have triggered a discharge.
Campaigners at Surfers against Sewage have a live map showing when there are sewage discharges along our coastlines. They believe that water companies release sewage regularly, even during dry periods. For example, their map showed two overflows on Southend Beach on 4 March, at a time of no rain.
Thames Water’s live EDM map
Thames Water (TW) is Britain’s largest water company and their reach extends into Essex. It’s the first company to publish a near-live map showing CSOs currently discharging. It will be legally required everywhere in 2025, so Thames is ahead of the game, and clearly open to closer scrutiny.

For example, for 15 days in January, the map showed sewage discharging into Pincey Brook in Essex. In February, spills were frequently logged after dry weather, for example, for an hour into Coopers Brook on 6 February. Environment Agency rules do not permit ‘dry spills’ (those that occur outside periods of heavy rain).
The huge number of recorded discharges is alarming. TW says the monitors are not infallible; that even a weed moving in front of one could set it off, incorrectly making it look active.
However, it’s curious that on 8 March, the first day of rainfall for weeks, the map suddenly showed 33 EDMs discharging. On 9 March, after more hours of sleet, about 73 EDMs showed red or orange. After some more drizzly rain on 10 March, there were over 120 EDMs on alert.
One might conclude that Thames Water can’t cope with light rain, let alone a real storm. And if all those EDMs are giving false readings when triggered by pondweed, then what use are they?
“Heartbroken”
In Episode Two of the BBC’s ‘Our Troubled Rivers‘, Paul Whitehouse reveals the vast amount of sewage that Thames Water allows to flow into the Thames. CEO Sarah Bentley says she is “heartbroken” about it and Thames plans to invest £1.6 billion to upgrade treatment works and sewers. It has committed to reducing “the annual duration of sewage discharges … by 50% by 2030, and by 80% in sensitive catchments”.
Bentley believes that middle-class customers should pay more to clean up rivers. “For some, it is affordable – and we should be paying more for it,” she says. However, Bentley herself earned remuneration of over £2 million in 2021–22. Feargal Sharkey, a leading campaigner against sewage in rivers, questions whether she should receive a huge salary and bonus while presiding over environmental damage to Thames waterways.
Many people are angry, as well as heartbroken, that sewage gushes into our rivers, not just ‘exceptionally’, but routinely.