Untreated sewage is being dumped illegally in rivers across England and Wales on a regular basis
Seven water companies in England and Wales discharged untreated sewage into rivers and the sea more than 3,000 times between 2017 and 2021
The water industry admitted action was needed to address the problem
MPs warned of a "chemical cocktail" of pollutants tainting England's rivers, including raw sewage and microplastics
Peter Hammond, a retired professor of computational biology and campaigner with Windrush Against Sewage Pollution, criticized the water industry for flouting poor regulation by the Environment Agency
Seven companies - Southern Water, South West Water, Thames Water, United Utilities, Wessex Water, Yorkshire Water, and Welsh Water - discharged untreated sewage from 59 treatment works that treat 4.5 million people's wastewater
Water companies are allowed to discharge untreated sewage into rivers in exceptional circumstances, such as during heavy rainfall
Water companies can be acting illegally if they discharge untreated sewage when conditions are dry (dry spill) or if they do not treat enough of the sewage before discharging it (early spill)
Prof Hammond analyzed data from "event duration monitors" to check if treatment works are discharging untreated sewage into rivers
United Utilities, Southern Water, and Welsh Water questioned the accuracy of some data, while Yorkshire Water disputed Prof Hammond's understanding of the data
The sewage treatment works at Dorking run by Thames Water had the highest number of unpermitted spills, discharging untreated sewage into the River Mole on 223 days over the last four years
Thames Water stated that all discharges of untreated sewage are unacceptable and they are determined to work with authorities to stop them from being necessary
Prof Hammond criticized the Environment Agency for failing to detect thousands of illegal spills due to insufficient scrutiny of available data
Water UK acknowledged the urgent need for action to tackle the harm caused to the environment by overflows
An Environment Agency spokesperson stated that they will pursue water companies for non-compliance and take appropriate action
1,300 storm overflows and storm tanks at waste water treatment works have been identified as "spilling frequently," and a major investigation into possible unauthorised spills at thousands of sewage treatment works is ongoing