Thames Water stops washing-up winding-up in the Wealdstone Brook

Last reviewed:

3 August 2016

Forty-two appliances, including sinks and toilets, no longer empty their loads into the Wealdstone Brook thanks to three years of hard graft by Thames Water and the Environment Agency.

In 2013 extensive detective work began in Harrow after dirty water, which should have been destined for sewer pipes and the local treatment works, was found to be running into drains meant only for surface water (rainwater from homes) and then out into the brook, a tributary of the River Brent.

The Environment Agency suspected that houses had incorrectly connected their wastewater pipes (for dirty water from appliances like toilets and showers) into the surface water pipe network, prompting an investigation by Thames Water into 362 homes south of Woodcock Park and north of Preston Hill.

An astonishing 6% of homes were found to be connected to the wrong pipes, and by the close of the investigation in December 2015, 42 household appliances (including four toilets) were found to be emptying straight into the brook.

Following the successful identification of the problem properties, Thames Water worked with home owners to make sure their pipes were properly reconnected.

Jonathan Evans, from Thames Water’s environment team, said: "No one wants toilets emptying directly into their local river so it’s a great feeling to have sorted this problem out and improved the water quality in the brook. Thankfully recent Environment Agency reports show pollution levels have significantly reduced. We’ve got a massive job still to do to trace more of these misconnections across our patch – so it’s really important that anyone having extensions built or carrying out plumbing work employs a reputable plumber and knows exactly where their wastewater is heading.”

Gemma Sloan, environment officer at the Environment Agency, added: "The Environment Agency is really pleased that Thames Water’s hard work has helped clean up this wastewater. Washing machines, showers and toilets were regularly discharging into the watercourse and reducing the water quality for the wildlife and creating an unpleasant environment in the brook. To ensure that this doesn’t happen again in the future we encourage homeowners to check that they are connected right – you can find information on how to do this on the ConnectRight website (”

Initial investigations to identify problem areas involved the Thames Water team hanging wire cages inside the drain network to catch toilet and kitchen waste and other evidence of pollution as it was flushed out of toilets and taps and along to the watercourse.

Once the hotspots were identified further detective work was carried out, including household surveys, CCTV surveys and placing colourful dye into toilets to trace where it flushed.

In the Thames Water region, plumbing mistakes result in up to one in 10 households misconnecting their waste appliances to the surface water system. This is the equivalent of almost two Olympic-size swimming pools of wastewater wrongly entering the region’s rivers and streams every day.

The Thames Water misconnections team work in close partnership with the Environment Agency to trace and reduce the number of misconnections, but it is predicted that there are at least another 60,000 misconnections still to be found.