England and Wales water firms show 99.97% compliance for drinking water quality

Annual reports from the Drinking Water Inspectorate for England and Wales both showed that 99.97% of water supply quality tests were compliant with standards in 2022 under each jurisdiction.

The watchdog found that coliforms were responsible for the largest proportion of breaches in both countries. In England about half of 1,016 non-compliant samples were related to coliforms whiel in Wales 40% of 68 non-compliant samples were coliform related.

Ten of the 17 public water companies assessed exceeded Ofwat’s penalties level of two for their compliance risk index (CRI) – a measure of “the risk to consumers from non-compliance with standards”. Five companies topped the industry average CRI of five. Dŵr Cymru’s CRI was just above the industry average while Severn Trent Water subsidiary, Hafren Dyfrdwr, scored 0.56.

Among the companies in England, treatment works was the site type that produced the greatest CRI score followed by consumer taps. Coliform bacteria was, by far, the parameter with the highest contribution to CRI at 47%. The next highest were iron level, water treatment works turbidity and taste each at 8%.