After persistently denying any wrongdoing, Welsh Water has finally conceded it has been polluting the River Teifi with untreated raw sewage for decades.

Data compiled by mathematician and former UCL professor Peter Hammond, shared with the BBC, confirms that the River Teifi has suffered a higher level of pollution than any other river in Wales.

This is the result of a highly inadequate wastewater treatment plant situated close to the town’s cemetery which has continued discharging sewage into the Teifi despite it never having been treated. The Cardigan plant is situated just two miles from Poppit Sands in St Dogmaels, which is a designated bathing beach that currently has a water quality of ‘excellent’.

"This is the worst sewage works I've come across in terms of illegal discharges," commented Professor Hammond in his report.

The Cardigan plant has illegally spilled for more than 200 days each year from 2019-2022.

Welsh Water is required to treat 88 litres of water a second before discharging waters, however the Cardigan plant continued to spill untreated sewage for a cumulative total of 1,146 days from the start of 2018 to the end of May 2023.

The news has been met with anger from Cardigan residents who have been urging Welsh Water to investigate spills in the Teifi for decades.

“It’s totally unbelievable that this has been allowed to happen for so long and I'm extremely disappointed with Welsh Water's admission,” commented county councillor Elaine Evans.

“I walk my dog on Poppit every day and the scum that can be seen coming down the river is disgusting.

“These figures equate to three illegal spills every single day in Cardigan alone. And Welsh Water has known all along what they’ve been doing.

”Cardigan is a beautiful area for the locals and tourists alike, so this appalling situation must be addressed as a matter of urgency."

There are also concerns that the discovery could now have a damaging impact on the number of tourists who visit Cardigan and the surrounding area.

“This is appalling news and very disappointing for the town,” commented Iona Jones.

“People were aware of this problem with raw sewage being released into our local rivers but definitely not on this level. Let’s hope this doesn’t have a negative impact on tourism in Ceredigion and that Dwr Cymru addresses the problem immediately. We pay our water rates so surely we deserve better than this.”

The wastewater treatment plant was installed in Cardigan in 2004, with the intention of filtering sewage through a membrane.

However the system was incapable of treating the amount of water that enters the plant and during Spring tides, saltwater gets into the pipes causing bacteria to release an enzyme that blocks the membrane. As a result, the plant regularly fails to treat the correct amount of sewage, causing it to spill it into the estuary.

“We’ve been consistently lied to by Welsh Water,” commented long-time campaigner Piers Partridge.

“We’ve been to so many meetings over the years where Welsh Water never revealed to us that the plant was broken and that raw sewage has been allowed to spill into the river since before records began.

“Should we now start thinking about reclaiming money that we’ve all been paying to Welsh Water, believing that they were treating the wastewater accordingly? Maybe there should now be a legal investigation?”

Natural Resources Wales has confirmed that it has been aware of the Cardigan issue for the past eight years and has served numerous enforcement notices on the plant. However no fines have as yet been issued.

“We’re not proud of this at all,” commented a Welsh Water spokesperson following this week’s discovery.

“For someone who really cares about the environment, it’s a very uncomfortable position to be in. But it’s not for the want of trying.

“We have extensive monitoring arrangements, amongst the most extensive in the sector, which we use to monitor our sites, but each site presents its own and sometimes very complex challenges

“Regarding the Cardigan works specifically, we had already identified the issue there being linked to saltwater entering the works which impacts the treatment process. 

"We reported this to NRW and agreed to undertake investment to improve the situation. Whilst this initial upgrade made some improvement, we are investing a further £20m at the site in 2025 to ensure full compliance with the discharge permit.

"Our discovery of issues at Cardigan have been fully disclosed to NRW from the earliest opportunity in line with our usual approach to dealing with these issues.”