Wales’ first river bathing waters over safe bacterial limits on 8 of 29 days tested in 2024
Bacterial tests performed by Dŵr Cymru Welsh Water (DCWW), Natural Resource Wales (NRW) and University of York/Friends of the River Wye (FORW) have shown that out of 29 days that the River Wye at the Warren - a popular swimming spot in Hay-on-Wye - was tested for bacteria in 2024, the water was above safe levels on 8.
Tests measured both E. coli and intestinal enterococci, which are considered a threat to human health once levels exceed 900 CFU (colony-forming units) per 100ml of water and 330 CFU per 100ml of water respectively. Fortnightly tests were carried out by NRW (6 days, data available here) across the course of the bathing season from 10th July - 20th September, weekly tests were carried out by DCWW from 28th May - 1st October and 3 days were tested (for E. coli only) by FORW during a single week from 28th July - 2nd August.
E. coli levels exceeded “safe limits” of 900 CFU/100ml on 6 out of 28 days tested
Intestinal enterococci levels exceeded “safe levels” of 330 CFU/100ml on 7 out of 26 days tested
In total, 29 days were tested and on 8 days one or both forms of bacteria were found to be above safe levels. It is with real concern that we report these numbers, given that the local community swim at this location regularly throughout the period reported. With the warm weather in 2025 so far we have already seen reports of potential illness from swimming, including a warning issued bya local high school on May 2nd that pupils had reported stomach illnesses after swimming at the Warren.
With the 2025 bathing season commencing, we call on Natural Resources Wales to provide the public with information as to what they are doing to determine the origin of these bacteria (including whether it is of human or animal origin) and resolve the unsafe levels being detected at this important and historic swimming spot (the Warren was marked on Ordnance Survey maps as a “Bathing Place” in 1888, and is the first river bathing place in Wales).