New City Hall analysis from the London Assembly shows instances of sewage flowing into London’s rivers in 2023 were almost five times the amount for the same period the previous year.

River Thames & Parliament - image courtesy Phillip Reiner 

The new analysis comes from published Thames Water data which monitors discharge from 118 sites across the Thames Water network feeding into 33 rivers and waterways.

The data shows that:

• between April and December 2023, Thames Water released sewage into London's waterways for 6,590 hours, 11 minutes and 54 seconds – a five-fold increase on the same period the previous year.
• in just six days, between 25 December and 31 December 2023, sewage was discharged across the Thames Water network for 128 hours and 12 minutes, equivalent to 18 hours every day. The discharges include both treated sewage and overflows of untreated sewage and storm water into rivers during high rainfall.

Mayor of London: "Thames Water urgently need to up their up their game"

Mayor of London Sadiq Khan commented:

“London’s rivers are the arteries of our city. Frankly the current state of some of our rivers is appalling and only getting worse. Thames Water urgently need to up their up their game, and get a grip of the situation. At the same time, ministers are standing by and letting more and more dirty sewage flow into our rivers. We need tougher legislation that forces water companies to act as a matter of urgency.

“While we’re making huge progress cleaning up London’s air and much of the capital’s environment, it’s a scandal that levels of sewage in our rivers are increasing at the same time.”

SadiqKhan has written to the new Thames Water CEO Chris Weston, urging him to get a grip on the situation and ensure that London’s rivers are clean, healthy, and protected from sewer spills.

In his letter the Mayor has highlighted the scale of the challenge that decades of under investment has led to London now having no healthy rivers. He urged Chris Weston to urgently get to grips with the problem and asked for reassurance that the organisation “will fulfil its obligations on environment including cleaning up our rivers and tackle pollution discharges”.

Sadiq Khan gave the example of the River Wandle – which was the last London river to lose its “good” status in summer of 2023 – which is now set to have sewage spills continuing until at least 2035.

Thames 21 - "Thames Water has underinvested in their sewerage infrastructure for many years"

Liz Gyekye, Communications Manager at Thames21, said:

“Thames Water has underinvested in their sewerage infrastructure for many years and desperately needs to modernise its network to prevent unacceptable sewage spills.

“London-based NGOs, including ourselves, are urging Thames Water to expedite the implementation of 357,000 rain gardens across London by 2040, rather than the proposed timeline of 2050 outlined in Thames Water's current business plan.

“This accelerated action is imperative to protect and restore London’s rivers from the ravages of sewage pollution as well as preventing the effects climate chaos on Londoners, as rain gardens help to prevent sewage pollution by holding flood water and helping to reduce the speed of it entering the sewerage systems.”

In addition to the poor level of service Thames Water has been providing for Londoners, the Mayor is also calling on ministers to do more to get a grip of the crisis.

Sadiq Khan is calling on the Government to:

• Develop a plan to guide Thames Water back to strong financial health in a way which doesn’t delaying the cleaning up of London’s rivers
• Deliver the essential water network upgrades that are needed, while protecting Londoners from increased bills.
• Introduce tougher legislation that forces water companies to end sewage discharge into rivers. This should include tougher penalties for water companies.

James Wallace, CEO of campaign group, River Action commented:

“With the London Mayoral election just a few weeks away, it is essential that the public sees a genuine commitment to urgency and leadership from City Hall to tackle the dreadful state of the River Thames.

“For decades Thames Water has got away with polluting our waterways, wasting drinking water and threatening the health and livelihoods of Londoners with impunity.

“We welcome political leaders committing to holding profiteering water companies and the failing Government regulators - the Environment Agency and Ofwat - to account.

“As cyclical floods and droughts worsen and the impact of aging infrastructure and population growth hit the most vulnerable and our precious wildlife, we need the Mayor of London to prioritise water quality and supply alongside other essential services.

“We hope the Mayor will not rest until Thames Water and the regulators are properly scrutinised and emergency plans are in place to secure London’s lifeblood, freshwater.”