Thames Water has committed "environmental crimes" by dumping at least 72 billion litres of sewage into the River Thames since 2020, new figures reveal.
Last year alone at least 14.3 billion litres of sewage were discharged into the river and 32 billion in 2021 - making it the worst year on record for sewage discharges into the Thames.
Modgen near Twickenham was the worst hit, with 17.1 billion litres being discharged there since 2020, an environmental information request submitted by the Liberal Democrats has revealed.
On one day in January 2021, Thames Water discharged almost one billion litres of sewage at the Modgen site.
Liberal Democrat MP for Twickenham Munira Wilson said Thames Water was destroying wildlife.
She accused the Government of "standing idly by" while rivers are "poisoned".
"These water firms are committing environmental crimes which are destroying our rivers and wildlife habitats, all whilst pocketing eye-watering sums of money," she said.
"With almost every sewage monitor unable to measure the litres of sewage discharged, this figure is likely to enter the trillions. Water firms are fitting monitors which simply aren’t up to the job and hide the true horrors of their filthy sewage habits.
"The Government should force Thames Water to install new monitors which measure the volume of sewage discharged, so we can find the areas which need saving the most from this awful act."
The second most impacted site was in East London, where 15.8 billion litres of sewage has been discharged at Crossness since 2020.
The Lib Dems are demanding water firms become "public good companies", which includes placing environmentalists on their boards and no longer allowing them to put profit before protecting the environment.
Water firms have no legal obligation to report the volume of sewage discharged, only the duration of the discharge.
Thames Water owns sewage monitors which measure volume and they were used while constructing the Thames Tideway project, the Lib Dems claimed.
These are the only known sewage monitors of their kind fitted in the country, and do not cover the entire network, the political party said.
The total volume of sewage discharged into the Thames is therefore predicted to be significantly higher than figures released on Friday.
But a Thames Water spokesperson said: "Our EDM monitoring equipment cannot measure volumes and was not designed to do so.
"With respect to the duration of sewage discharge, near real-time data is published for each of our 468 permitted discharge locations.
"This data gives the number and duration of discharges via our dedicated website. At a limited number of sites relating to the Tideway Tunnel, we have the ability to calculate volume discharged however we do not do this on a regular basis across our sites.
“What matters most is stopping the need for the discharges and we have published plans to upgrade over 250 of our sewage treatment works and sewers.
"In London, we have started the £100 million upgrade of Mogden sewage treatment works, which will increase capacity and reduce the number of storm discharges from the site, and we’re also spending £145 million upgrading Beckton sewage works. We’re currently increasing sewage treatment capacity at a number of our other sewage works across the Thames Valley, including Witney to be completed by 2025.
"In addition, the Thames Tideway Tunnel, a £4 billion investment, is nearing completion and will capture 95 per cent of the volume of untreated sewage currently entering the tidal Thames in a typical year."
In April the Standard revealed that sewage poured into London’s rivers for almost 7,000 hours last year.
The Thames saw 769 toxic spills lasting a total of 3,286 hours — more than 136 days. The River Roding, which flows through Essex and London and forms Barking Creek as it reaches the Thames, had the second highest number of sewage releases in the capital at 237.
A map released by Thames Water in January shows where storm overflows are discharging in real time, and the date and time of the last recorded discharge.
In June London Mayor Sadiq Khan said the crisis at Thames Water proves that "privatising basic utilities hasn’t worked", as he criticised the monopoly enjoyed by the company.
The firm, which provides water to around one in four people in Britain, faced questions over its future, as it grapples with a £14bn debt pile.
Former chief executive Sarah Bentley stepped down with immediate effect after she gave up her bonus due to the company’s environmental performance.
Earlier this year Thames Water was handed a £3.3 million fine for a "reckless" incident in which "millions of litres" of undiluted sewage was pumped into rivers near Gatwick Airport in 2017.
