Brief

ZSL reports dozens of sewage misconnections polluting London’s rivers

The Zoological Society of London’s Outback Safari programme identified dozens of household plumbing faults discharging raw sewage into four London rivers.

By Felo News Desk · Published Mon, 12 Oct 2026 02:37:10 GMT

Volunteer‑led inspections by the Zoological Society of London (ZSL) have uncovered dozens of household plumbing misconnections that are sending raw sewage directly into the River Brent, River Wandle, River Ravensbourne and River Pinn, according to a survey published on 11 October 2026.

What happened

The Outfall Safari programme, which trains volunteers to patrol riverbanks, inspected 22.4 km of the River Brent, 105 surface‑water outfalls on the Wandle, and additional sites on the Ravensbourne and Pinn. Inspectors recorded 44 "polluting outfalls" on the Brent, nine active leaks on the Wandle, 18 outfalls on the Ravensbourne (six triggering emergency alerts) and several unnamed outfalls on the Pinn.

What the reports add

Standard.co.uk notes that the Brent was described by ZSL project officer Ella Carbery‑Tarrant as a "hotspot for poor water quality" and that raw sewage is being discharged directly into the river. The same outlet reports that a full‑time enforcement officer was appointed by City Hall last month to address misconnections across west London. On the Wandle, 90 of the 105 inspected outfalls showed no visible contamination, but nine were actively polluting, including two severe leaks that prompted immediate alerts to Thames Water and the Environment Agency.

What was said

Ella Carbery‑Tarrant, project officer for ZSL’s Outfall Safari, said the state of some watercourses is "pretty disgusting" and called the Brent "a hotspot for poor water quality". She added that "there are some pretty bad surface water outfalls that are polluting a lot of watercourse".

How it came about

The Outfall Safari programme has been running for a decade, training volunteers to identify drainage pipes that discharge household sewage into waterways instead of the sewer system. Misconnections often arise after home renovations or improvements, and can affect single properties, whole blocks of flats or entire housing estates. The recent audit prompted emergency alerts to Thames Water for 15 high‑priority incidents on the Brent and triggered action from the Environment Agency on the Wandle and Ravensbourne.

Key facts

The survey identified 44 polluting outfalls on the River Brent out of 123 inspected sites. (standard.co.uk)
Nine active leaks were found on the River Wandle, including two severe leaks that triggered emergency alerts. (standard.co.uk)
Eighteen polluting outfalls were recorded on the River Ravensbourne, six of which required emergency alerts. (standard.co.uk)
A full‑time enforcement officer was appointed by City Hall to tackle misconnections across west London. (standard.co.uk)
Ella Carbery‑Tarrant described the condition of the rivers as "pretty disgusting". (standard.co.uk)