2024 Illegal Spilling: The Worst Yet for Windermere
Once again, we’re teaming up with our brilliant allies at Windrush Against Sewage Pollution to share the findings of our latest joint study. Sewage dumping in Windermere has been a long-standing scandal—but 2024 marked a shocking new low, with more illegal spilling days than we've ever recorded in any previous report.
This is a national disgrace. This isn’t just about a lack of investment in infrastructure—it’s about a system that puts shareholder profits ahead of the environment, the economy, and the cultural importance of England’s most iconic lake.
Buckle up, because we are not happy.
Meet Professor Peter Hammond
Firstly, it’s worth properly introducing Professor Peter Hammond. He and Windrush Against Sewage Pollution (WASP) have done more than anyone in the country to expose the failings of the water industry.
Peter’s landmark 2021 study, titled “Detection of Untreated Sewage Discharges to Watercourses Using Machine Learning”, revealed the extent of illegal sewage dumping across the UK. His work is so respected that, during an Environmental Audit Committee hearing, MPs acknowledged that his findings surpassed even those of the Environment Agency—the regulator responsible for spotting these spills.
His research is robust, scientific, and not easily challenged. When we say we trust his analysis, we mean it. We go on national TV and tell the country that United Utilities has illegally dumped sewage into Windermere—because the data, which we obtained from United Utilities itself, proves it.
Even water companies like Thames Water don’t dispute Peter’s findings. In fact, OFWAT has used his work as the basis for its recent proposed fines against water companies.
You’ll hear United Utilities cry that the analysis is wrong—but they've failed to provide any evidence to disprove any of the illegal spills revealed in this report. The BBC asked them to explain why it was incorrect. They couldn’t—or wouldn’t—do it.
Illegal spilling in Windermere
Today's report focuses on early illegal spilling.
So, what is early spilling? It’s when sewage is discharged before a treatment works has reached its legally permitted flow-to-full-treatment (FTFT) rate. Treatment plants are required to process a certain volume of sewage (litres per second) before any overflow can legally occur. Discharging before reaching this required pass-forward rate is illegal.
By cross-referencing flow data (the amount of sewage directed to treatment works) with EDM logs (which track discharge duration into the lake), this report uncovers both the number of illegal discharges and their duration.
Professor Hammond's analysis has identified 140 days with illegal spills in and around Windermere in 2024. This takes the total number of days with illegal spills in the catchment to over 600 since 2018. Every one of the six sites that discharge untreated sewage into the lake has spilled illegally at some point, clearly showing a systemic lack of capacity as a result of chronic underinvestment. This exemplifies the total failure to protect England’s largest and most culturally significant lake, laying bare the deep and damaging flaws of privatisation.
Since 2020, those same six sites have discharged untreated sewage for a staggering 33,410 hours—that’s the equivalent of 1,392 full days. For context, there are only 1,827 days between 2020 and 2024.
And to be clear: this report only looks at untreated sewage. Treated sewage, which can also significantly damage Windermere’s fragile freshwater ecology, continues to be discharged daily—but we’re leaving that aside for now.
Early spilling is the most prevalent form of illegal spilling happening in Windermere, yet the Environment Agency is failing to ask for the right data to uncover it. The EA could access the data required to hold United Utilities accountable, but they are simply not doing it.
Fighting United Utilities for Transparency
We obtained the data used in this report through the Environmental Information Regulations (EIR). To enable Peter Hammond’s analysis, we specifically requested five datasets:
15-minute final effluent flow data
Individual spill start/stop times (from Event Duration Monitoring)
All telemetry data between the wastewater treatment works (WwTW) and United Utilities’ waste operations control centre
Dates of site visits by operations staff
Copies of operator logbook entries
Unsurprisingly, United Utilities was not forthcoming. We had to go through the full legal process to obtain this data:
We made an initial request. Denied.
We requested an internal review, outlining key points for disclosure. Denied again.
We escalated the issue by filing a formal complaint with the Information Commissioner, arguing that the data was clearly in the public interest.
The Commissioner intervened and forced United Utilities to release the data.
Given what we’ve uncovered today, it’s no surprise that a £7 billion water company wanted to keep this information out of the public domain—and out of the hands of independent experts.
Why YOU Should Be Livid
This is the failure of privatisation laid bare. You have paid United Utilities for a service that, based on the evidence presented today, has not been delivered. Now they’re raising bills again—to fund upgrades they should’ve done years ago, while still prioritising shareholder dividends over public and environmental responsibility.
For Save Windermere, this is the crux of it: our lake is being systematically exploited. And those who are supposed to protect it—the Environment Agency, government departments, local organisations—have looked the other way. Those tasked with safeguarding our lake have failed, and others have watched this happen without challenge.
Save Windermere is now calling for:
The prosecution of United Utilities for repeated illegal discharges.
The removal of the Environment Agency’s board for regulatory failure.
An internal investigation into how illegal sewage discharges were missed.
An end to all sewage pollution into Windermere through long-term infrastructural investment.
While the government has pledged to work with us and local partners to eliminate all sewage discharges into Windermere, we need action to achieve this ambition. Save Windermere is now calling for that promise to be legally binding, ensuring that work begins immediately to protect England’s largest lake now and into the future, ensuring that Windermere can never be exploited again.
We want Windermere to be the flagship site for freshwater conservation in this country. This lake belongs to the people. Its cultural value shouldn't be confined to the past—it should define how we protect it now and into the future, ensuring a lasting environmental legacy for the region.
This is entirely achievable. It’s simply a matter of cost and political will.
To date, both the government and the regulator have turned a blind eye to the exploitation of England’s largest lake allowing United Utilities to pollute with impunity
Those who allowed this exploitation must now be held accountable—for what we believe to be criminal activity.
If you’re as outraged as we are and want to help us hold United Utilities to account, please consider supporting our work by making a donation below.
You can download Prof Hammond’s full report here.
