Pembrokeshire’s rivers are among the most polluted in the entire UK, figures released by the Welsh Liberal Democrats say.

A Welsh Liberal Democrat analysis of sewage dumping statistics released by Welsh Water/Dŵr Cymru says it paints a grim picture for west Wales, with Preseli Pembrokeshire, Ceredigion, and eastern Carmarthenshire all being in the top 10 constituencies in the UK for sewage dumping.

Welsh Liberal Democrats say the figures for West Wales show Preseli Pembrokeshire being polluted by sewage 5,003 times in 2022, lasting 45,902 hours, while Carmarthen West and South Pembrokeshire was polluted by sewage 3,563 times in 2022 – lasting 26,132 hours.

Neighbouring Ceredigion was polluted by sewage 3,681 times in 2022, lasting 30,817 hours.

In west Wales, the worst area was Carmarthen East and Dinefwr, polluted by sewage 6,756 times in 2022, lasting 57,409 hours.

The River Teifi is also ranked the ninth most sewage polluted in the entire UK with sewage being dumped in the river for 11,801 hours last year, Welsh Liberal Democrats say.

Welsh Liberal Democrat Leader Jane Dodds said: “It is utterly unacceptable that while rivers in regions like my own such as the Wye, Tawe, Usk, Teifi and Severn continue to seriously decline in health the bosses of Welsh Water are using the publics money to give themselves handsome bonuses rather than reinvest the money into infrastructure improvements.

“The whole thing makes a mockery of the idea Welsh Water is a ‘non-profit’. The Welsh and UK Governments must work to ban these bonuses and mandate the infrastructure improvements we need.

“Our rivers and the wildlife in them are running out of time.”

A spokesman for Welsh Water said: “We take our responsibility for protecting the environment seriously but understand the real concerns there are regarding the operation of storm overflows and can assure our customers that this is something we are listening to them about.

“With monitors now on over 99.5 per cent of our overflows, we are able to provide one of the most comprehensive reports on how our storm overflows perform. We are always open with this information by publishing it on our website and report the number of spills to our environmental regulators.

“We also provide real time spill information for key bathing waters to interested bodies, including Surfers Against Sewage and Rivers Trust.

“Our data for 2022 shows that we saw a 12 per cent reduction in the average number of storm releases per storm overflow compared 2021, from 43.5 to 38.3; and a 25 per cent reduction in total spill duration in 2022, from 807512 hrs to 602987.5 hrs

“While there has been a reduction, which in part is due to the investment work we are undertaking to reduce spills, the reduction has also been influenced by the dry weather we saw last year.

“The total removal of combined storm overflows from our system is unaffordable and would take decades and therefore is not an option but what is in our control is the ability to target investment to CSOs [Combined Storm Overflows] which have the biggest environmental impact.

“That is why we are investing significantly to improve CSOs with £140m being invested between 2020-2025 and a further £420m planned from 2025 to 2030.”

The spokesman added: “Our investment to date in our wastewater system has delivered real improvements and helped ensure Wales has over a third of the UKs Blue Flag beaches while only having 15 per cent of the coastline and that 40 per cent of our rivers and waterbodies meet good ecological status compared to 16 per cent in England.

“However, we recognise that with environmental legislation tightening and customer expectations changing, more needs to be done to protect bathing and river water quality.

“Equally as important as tackling CSO’s is tackling phosphorous pollution and we are delivering a comprehensive programme of upgrades to our wastewater treatment works that will remove 90 per cent of our phosphorous discharges by 2030.”