Drinking Water Inspectorate reports risk disparities for England and Wales

Water quality in England and Wales remains of a very high standard, but work remains to improve planning for future generations, the Drinking Water Inspectorate (DWI) reported in its annual reports for England and Wales.

The regulator's findings included risk disparities between England and Wales.

• The 2019 Compliance Risk Index (CRI) for England, which allocates a numerical value to risk, was 2.80 and 3.73 for Wales. A lower value indicates a lower risk. The DWI noted that from 2020, companies have a target to achieve an individual CRI of 2 as a common performance commitment. It said the median value in England for 2019 was 1.73 and “so over half of companies are now meeting this expectation. However, Southern Water are notable with a score of 7.66 which is over 4 times the current median value and of which 69% was due to coliforms at treatment works.” Meanwhile in Wales Welsh Water scored 4 of which three-quarters were due to aesthetic parameters, (iron, manganese, taste, odour).

• In 2019, there were 547 events in England and 46 in Wales. The Event Risk Index (ERI) rates the risk arising from these events, and a lower value indicates a lower risk. In 2019 the ERI for England was 723, while it was 27 for Wales (26 for Welsh Water and 48 for Hafren Dyfrdwy). The DWI said a performance target of 30 was considered acceptable.

“Over half of companies achieve this standard but of particular note are four companies in England: Northumbrian Water, United Utilities Water, Southern Water and Thames Water who were above the national ERI. Notably, Northumbrian Water were over 2.5 times the value of the next highest company due largely to an unplanned event at Whittle Dean works where Cryptosporidium was detected. All four companies will be subject to further scrutiny.”

The regulator noted as particular challenges for the industry: lead in domestic plumbing; global challenges such as Covid 19; and water resource demand and availability. It said consumer contacts in Wales are dominated by discolouration, while in England, compliance failures and unplanned events are dominated by microbiological parameters such as coliforms, E. coli and low-level Cryptosporidium detections.

High performer across all measures used by the DWI, Anglian Water said: "This was our best ever year for water quality standards and we have performed better than industry averages in all key areas."