Water companies’ environmental performance deteriorated last year despite £5bn of investment over the previous five years, a joint report by UK water regulators has found.

Eight of the nine English companies were rated 'poor' or 'requiring improvement'. Serious pollution remained a major concern, and the industry recorded its worst-ever environmental score: 16 out of a possible 36 stars.

The findings contrasted with stronger performance elsewhere. Drinking water quality remained high, while service disruptions decreased. Those improvements, however, did not extend to the industry’s overall environmental record.

Water UK attributed some pollution to external factors, including vandalism. Regulators also highlighted shortcomings in delivery, noting that many environmental improvement schemes had not been completed despite receiving funding.

Customers face higher charges despite the performance problems, with bills projected to rise by an average of 36% by 2030.

The government plans to overhaul the regulatory structure, with a potential increase in government ownership of water companies, as it seeks to address systemic failures and high household water consumption.