The water in Beverley Brook is not designated as of bathing quality, nor is it monitored regularly. Its main water source is treated water from the Hogsmill sewage treatment plant. The water may look clear, but we receive reports from time to time that dogs and children, as well as adults, have become sick after exposure.

Many of us are working to improve the habitat and water quality and we are delighted that water quality has improved in recent decades. In the past year we have recorded nine species of fish but, good as this is, these species are relatively resilient to poor water quality.

Please note:

• Recent surveys have shown that there are many drain misconnections introducing sewage into the brook – severe cases are reported when identified but can take up to 3 years to be resolved, as tracing the source and correcting it can be complex.
• The brook also has four Combined Sewer Outfalls where authorised discharges of untreated sewage can take place without notice – for details you can check the Thames Water website.
• Recent tests have also shown high levels of chemicals of emerging concern, including parasiticides, anti-depressants and ‘forever’ chemicals, most likely from treated wastewater discharged to the brook.

We started performing regular water quality testing for E. coli on the Beverley Brook at Barnes Green with the help of our citizen science volunteer group in autumn 2025. The latest results will be displayed on this page.

Published on: 25 June 2024

Last updated on: 2 November 2025