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NRW tackles hidden pollution threat from misconnected domestic pipes in Cardiff

27 Nov 2025 2 minute read
Grey staining in surface water network. Image: NRW

Natural Resources Wales (NRW) is taking action to address a lesser-known source of water pollution – misconnected household appliances.

Following several reports of pollution impacting the River Taff near Mynachdy Road in Cardiff and the River Ely near Michaelston-Super-Ely, NRW’s investigation uncovered more than 30 cases of misconnected wastewater pipes.

These included washing machines, toilets, sinks, and home extensions incorrectly connected to the surface water network instead of the sewer system, allowing untreated wastewater to flow directly into rivers, causing pollution and harming ecosystems.

NRW officers traced the pollution sources by checking nearby surface water outfalls that discharges into the rivers. Once they saw grey polluted water around the outfalls, they knew the pollution was likely caused by wastewater.

NRW is working closely with Dŵr Cymru Welsh Water to notify property owners and ensure corrective measures are taken. Letters are being issued to households to resolve these issues promptly.

Alex Grainger, Environment Officer for NRW, said: “Misconnections are a hidden but significant source of pollution and household plumbing errors can have a major impact on our rivers.

“We want to raise awareness of this issue and help fix these problems to protect the water quality in our rivers and wildlife.

“We encourage people to check their plumbing, and to contact Dŵr Cymru Welsh Water for advice or are concerned about a misconnection in their area.”

For guidance or to find out how to report suspected misconnections, visit www.dwrcymru.com/en/help-advice/misconnected-sewers

Pollution incidents should be reported online at www.naturalresources.wales/reportit or by calling NRW’s 24/7 incident line on 0300 065 3000.


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