This information was brought to light by an environmental information request submitted by the Liberal Democrats, who are urging water companies to be more transparent about sewage spills.
Under current regulations, water firms are not legally required to report the volume of sewage discharged, only the number of hours during which it was released. Campaigners argue that this approach is inadequate as it does not provide an accurate measurement of the amount of sewage in England’s rivers.
While volume measuring devices are not available in most areas, Thames Water uses sewage monitors to measure volume at some locations. However, since these monitors do not cover the entire network, it is likely that even more sewage was released than measured. In 2021, the worst year, at least 32 billion litres of sewage were discharged into the Thames, with Mogden near Twickenham being the most severely affected site, releasing 17.1 billion litres of sewage into the river.
Liberal Democrat MP for Twickenham, Munira Wilson, has called for Thames Water to be replaced by a “public good company” with an environmentalist board, prioritizing the environment over profits. She criticized the government for not taking more action to address these environmental issues, and stated that water firms must stop prioritizing profit over the environment.
Thames Water has faced prosecutions by the Environment Agency for pollution incidents, resulting in fines totaling £35.7 million between 2017 and 2023. Earlier this year, the company was fined £3.3 million for discharging untreated sewage into rivers, causing the deaths of over 1,400 fish.