Plans to carry out £42 million worth of investment along the Teifi – including £20 million in Cardigan – have been revealed by Dŵr Cymru.

Dŵr Cymru Welsh Water has confirmed that it plans to accelerate investment in its network of wastewater assets across Ceredigion to improve river water quality in the Teifi and help protect the wider environment.

This investment includes £20m investment in new a wastewater treatment works at Cardigan; £9m investment in four other wastewater treatment works along the Teifi river and £10.5m to reduce the impact of key storm overflows across the county.

A key focus of its investment plans will be to fully replace Cardigan Wastewater Treatment Works (WwTW).

This follows extensive work in recent years after it was identified that seawater enters the site from the tidal river, especially during spring high tides. This process, known as saline intrusion, affects the treatment process at the site and can result in Cardigan site not having the capacity needed to deal with wastewater entering the works.

This can cause local storm overflows to discharge more than they should into the local estuary, however, bathing waters in the area (Poppit Sands) continue to meet “excellent” water quality standard as monitored by Natural Resources Wales.

After carrying out extensive trials and installing two pilot treatment plants at Cardigan, Welsh Water has identified a process using moving bed bio-reactors. This process has proven to be the most effective in reducing the severity of incoming seawater, helping to reduce its impact and improve resilience at the works.

Work to install the new treatment works is due to begin in April 2025, and is expected to be completed by April 2027. In the meantime, Welsh Water is planning to install a temporary package treatment plant this month to help treat some of the stormwater entering the works and this will be in place until work to replace the treatment works at Cardigan is completed.

Welsh Water’s Managing Director of Wastewater Services, Steve Wilson, said: “We’ve been working hard in recent years to tackle these challenges at Cardigan wastewater treatment works which we do not experience at any of our other sites across Wales to the same extent. This has involved undertaking lengthy and complex investigations and we are sorry that this has taken so long.

“The plans are now being designed and will be delivered from 2025.”

The company has also confirmed investment in its wider network across the Teifi catchment which will include investing nearly £9 million in 4 key treatment works by the end of March 2025, namely Llanybydder (£3.5m), Pencader (£2.8m), Lampeter (£1.3m) and Cwrtnewydd (£1.2m).

This commitment will be supported by a separate investigation programme looking at the impact of storm overflows, which will see £10.5m invested in the Teifi catchment to prioritise and improve overflow.