Welsh Water admits illegally spilling sewage at dozens of treatment plants for years

WELSH WATER has admitted to spilling untreated sewage at dozens of treatment plants for years. Data shows that one of their worst performing plants is in Cardigan in West Wales, where the company has been spilling untreated sewage for at least a decade into an environmentally protected area near a rare dolphin habitat.

The findings came to light following an investigation by Peter Hammond, a former University College London professor who campaigns for Windrush Against Sewage Pollution.  

To compile the report, Hammond, who shared the results with BBC News, requested data on 11 Welsh treatment plants. He found that ten had been frequently releasing untreated sewage when they should have been treating it first, and that in total these 11 rivers and river catchments were exposed to illegal spills for over 100,000 hours.  

Of the 11, at least 419m L of untreated sewage was discharged from just four of the treatment works: Caernarfon, Llanfarian, Llanrwst, and Ruthin. A further report finding highlighted possible permit breaches for ammonia levels in treated sewage at the firm’s Garnswllt plant. 

Sewage plants are allowed to discharge or “spill” untreated sewage during periods of heavy rain to prevent plants becoming overwhelmed, and to stop waste backing up into homes.  

But to release untreated waste before a plant reaches the overflow level stipulated on its permit is an illegal breach. According to the data collected by Hammond, between 40 and 50 wastewater treatment plants run by Welsh Water are currently operating in breach of their permits. 

The permit at its treatment works in Cardigan, which serves over 7,000 people, requires the plant to treat 88 L/s of sewage before spilling. However, the report notes it illegally spilled untreated sewage on 1,146 days between January 2018 and May this year. 

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

The treatment plant spills into the Teifi estuary, one of only two areas around the UK hosting a semi-resident population of bottlenose dolphins. It is also designated as a Special Area of Conservation (SAC) and is home to Atlantic salmon, otters, and lamprey – a primitive, jawless fish that feed off other fish using a sucker mouth lined with teeth. 

Welsh Water, which did not dispute the analysis, said in response that the nearby Poppit Sands beach had water quality consistently rated as "excellent".   

Despite holding a prestigious Blue Flag award, an analysis of official Environment Agency figures for 2022 showed that Poppit beach was soiled by sewage discharge on no fewer than 79 separate occasions –  a figure that earned it the title of “the worst polluted Blue Flag beach in the whole of the UK”. 

Gail Davies-Walsh at rivers campaign group Afonydd Cymru, said: "Untreated sewage causes a host of problems on our rivers. High nutrient levels coming from sewage lead to algal blooms that lead to the depletion of oxygen in our rivers. And that clearly has knock-on impacts to our fish populations and to other species." 

It was Afonydd Cymru who advised Hammond to investigate a number of Welsh Water’s sewage works following concerns over compliance against their discharge permits. The firm was already on the campaign group’s watchlist due to an investigation by OfWat for leakage and Per Capita Consumption (PCC) miscalculation, and for being looked at by the Environment Agency and Ofwat for issues at wastewater treatment works in England. 

Along with the damning findings pertaining to Welsh Water, the report also revealed that the long-term breaches at the site were known about by Natural Resources Wales (NRW), who allowed the discharges to continue for up to ten years without any significant action.  

During that time, only two enforcement notices − but no prosecutions or fines − were served on Welsh Water by the environmental regulator, which downgraded the company this year following what it called a continuing “disappointing” environmental performance. 

Along with pollution incidents rising by 7% in 2022 compared with the previous year, the company only self-reported two out of four incidents, in comparison with six out of eight incidents in 2021. 

Earlier this month, Welsh Water, a not-for-profit company, said it is committing to investing nearly £1.9bn (US$2.3bn) into environmental measures between 2025 and 2030. This will include embarking on a multi-Asset Management Plan (AMP) programme to stop its network of 2,300 storm overflows causing ecological harm to rivers in its operating area.  

The average monthly bill will need to be £5 higher in 2025 and rise £10 by 2030 to support this ambitious funding, but research by the firm has shown that 84% of customers find the plan acceptable. 

Welsh Water is also spending £20m on a new wastewater treatment works at Cardigan. Work to install the new treatment works is due to begin in April 2025, and is expected to be completed by April 2027.