UK water environment assessment: a mixed picture, with progress where accountability is clear

Undertaken under the Environment Act 2021, the assessment presents a mixed picture for clean and plentiful water. Environmental trends remain varied, and overall prospects of meeting key ambitions are assessed as largely off track. However, the detail is important. Progress is identified in specific areas, particularly where delivery relies mainly on the water industry and accountability is clearly defined. Reductions in pollution from sewage treatment works for some key pollutants, alongside falling leakage and per capita water consumption, are highlighted as areas of improvement during the reporting period. These improvements reflect sustained regulatory pressure, targeted investment and well-established performance frameworks.

At the same time, the wider state of the water environment remains largely unchanged. Ecological status shows little improvement and bathing water quality has declined. The assessment indicates that progress is strongest where responsibility is clearly assigned, performance is measured and funding is aligned to delivery, while outcomes that depend on multiple sectors, diffuse pressures or long-term physical modification of water bodies have proved much harder to improve.

A changing policy and regulatory context

The reporting period covered by the assessment coincides with significant developments in the governance of the water sector. The Water (Special Measures) Act, enacted in early 2025, aims to strengthen the regulation and oversight of water and sewerage companies. Statutory Drainage and Wastewater Management Plans are now in place, reinforcing long-term planning for sewerage systems and storm overflows. At the same time, AMP8 represents a record level of investment intended to improve services, enhance resilience and protect the natural environment.

Overlaying these developments is the Independent Water Commission’s review of the sector and its call for a fundamental reset of long-term planning and regulation. The Commission’s recommendations, and the government’s stated intention to reform regulatory structures, create both opportunity and uncertainty for the industry.

From the OEP’s perspective, these reforms have the potential to improve coherence, accountability and long-term outcomes. However, the assessment also cautions that reform processes can divert attention from implementation. Many of the challenges identified in the report are not due to gaps in legislation or ambition, but to the pace, scale and coordination of delivery. For water companies, this reinforces the importance of maintaining operational focus during a period of structural change.

Environmental trends most relevant to water companies

The report reviews a wide range of indicators, but several trends stand out for their direct relevance to water company activity.

Continuous loads discharged from sewage treatment works show an overall reduction between 2020 and 2024, although trends differ by pollutant. Phosphorus loads have declined, reflecting targeted investment and treatment upgrades. Ammonia loads have not reduced further, and biological oxygen demand has increased, underlining the need for continued attention to treatment performance and environmental outcomes.

Leakage and potable water demand have declined across all major components of public water supply. Household demand, the largest component, and leakage have both fallen with statistical significance. Non-household demand has also declined, though less consistently. These trends support progress towards the Environment Act target to reduce per capita water consumption, even as drought conditions and climate variability pose increasing challenges.

Trends support progress towards the Environment Act target to reduce per capita water consumption, even as drought conditions and climate variability pose increasing challenges

At the same time, the assessment identifies trends that continue to affect water quality and environmental outcomes. Soil nutrient balances have deteriorated, increasing the risk of diffuse pollution from agriculture. Pollution incidents to water have increased, based on Environment Agency data that records incidents from a range of source categories. While public and media attention has focused particularly on sewer overflows, the assessment considers pollution incidents across the water environment as a whole. The ecological condition of small water bodies also remains poorly understood, with the assessment highlighting gaps in monitoring and evidence.

For the industry, these findings reinforce a familiar message: improvements in asset performance and operational efficiency are necessary but not sufficient to deliver system-wide environmental recovery.

Key messages from the assessment: clean and plentiful water

Taken together, the assessment does not identify a lack of ambition or policy intent in relation to clean and plentiful water. Instead, it brings into focus a set of concrete findings about outcomes, evidence and delivery that shape the overall picture of progress.

• Despite targeted improvements in some pressure areas, the overall ecological status of surface waters shows little change, with only a small proportion of water bodies achieving good ecological status or potential.
• The assessment highlights limitations in monitoring and evidence that constrain the ability to assess outcomes comprehensively, particularly where links between action and environmental condition are indirect or cumulative.
• Several major pressures affecting water quality — including agricultural diffuse pollution, physical modification of water bodies and pollution from abandoned metal mines — continue to show mixed or limited progress.
• The assessment is clear that these findings reflect issues of delivery and coherence rather than the absence of legislation or ambition.

Finally, the assessment situates progress on clean and plentiful water within a broader period of regulatory change, while underlining the continued importance of implementing existing commitments effectively.