The Shocking Truth Behind Our Worst Sewage Spillers in 2024
Dŵr Cymru Welsh Water, the company responsible for most of Wales' wastewater, is discharging raw sewage into our rivers for thousands of hours every year. And in 2024, the data hit new highs. This new data revealed the worst offending sewage overflows by total time spilled and number of discharges.
The Worst by Time: How Long Were They Spilling?
The top three worst sewage overflows by total hours spilled in Wales in 2024 are:
Pwllmeyric SPS (WUF catchment)
Spilled 6,266.75 hours over 278 incidents.
That's 261 days, or almost 9 months of nonstop pollution.
Cwm Penmachno WwTW Settled Storm (NWRT catchment)
Spilled 5,976.00 hours over 270 incidents.
249 days, or over 8 months.
Reynoldston WwTW Settled Storm (SEWRT catchment)
Spilled 5,302.00 hours over 253 incidents.
That's 221 days, or over 7 months.
These sites alone dumped untreated waste into rivers for a combined over 1.5 years of time.
Top Offenders in the North Wales Rivers Trust Catchment
In our patch alone, five sites are causing ecological chaos:
Cwm Penmachno: 5,976 hours (Afon Machno) — 68.2% of the year
Llangybi, Pwllheli: 4,678.75 hours (Afon Ddu) — 53.4% of the year
Commins Coch: 4,270.50 hours (Afon Dyfi) — 48.8% of the year
Bryngwran: 3,983.75 hours — 45.5% of the year
Llan Ffestiniog: 3,666.00 hours — 41.9% of the year
These are not isolated cases. This is a systemic failure.
The graph above shows just how much of the year these sites were spilling. In some cases, over two-thirds of the entire year was polluted.
Most Frequent Spillers in Wales
It’s not just about hours. Sometimes, it’s about volume. Here are the sites with the most number of counted spills:
Connah's Quay Syphons: 367 spills (3,998 hours)
Llan Ffestiniog STW: 361 spills (3,666 hours)
Camrose STW: 345 spills (4,479 hours)
The Curious Case of Llanbrynmair
Llanbrynmair, once topping the charts for years, is not in the top 3 for the first time since 2020. After campaigning for changes last year we are pleased to see that Dŵr Cymru have acted to improve these works. Although just downstream Commins Coch have now appeared as the third worst in our catchment. We will be investigating if there are any links to the Llanbrynmair works.
Enough is Enough
These aren't minor leaks. These are months upon months of raw sewage entering some of Wales' most cherished rivers and ecosystems. We need urgent investment in infrastructure, transparency from Dŵr Cymru, and meaningful action from regulators.