Water and sewerage companies in England and Wales are being placed under new legal duties to cut pollution, after regulators published detailed instructions on how firms must prepare and publish annual Pollution Incident Reduction Plans (PIRPs).
Under provisions inserted into the Water Industry Act 1991 by the Water (Special Measures) Act 2025, every “relevant undertaker” — including incumbent firms and new appointees providing water, sewerage, or both — must publish a PIRP on its website before 1 April 2026, and then every year. From 1 April 2027, companies must also publish an annual Implementation Report assessing how well they delivered the measures promised in the previous plan.
The guidance, issued on 8 January 2026, sets out how regulators will judge whether plans are legally compliant and warns that failure to publish required documents can amount to an offence by both the company and its chief executive. Plans and reports must be easy to find from a company’s homepage, remain accessible for at least five years, and must not be altered after publication. Each PIRP and Implementation Report must include, or be published with, a statement confirming the chief executive has personally approved the documents.
Companies are required to review the previous calendar year’s pollution incidents and set out how they will reduce incidents in the next calendar year. In particular, plans must cover:
- the frequency and seriousness of pollution incidents recorded in the previous calendar year
- the immediate and root causes of those incidents, including systemic failures
- the steps already taken to maintain assets and reduce pollution
- additional measures planned, their expected impact, and implementation timescales
The guidance mandates a structured approach using tables and standardised measures. Firms must break down reporting by relevant asset types — including foul sewers, combined sewer overflows, rising mains, pumping stations, treatment works, storm tanks, and clean-water networks — and provide month-by-month counts of incidents by severity category.
For serious incidents, companies must list event details and root causes. For Category 3 incidents, they must quantify root-cause patterns and, in many cases, the percentage share of incidents attributable to each cause. Plans must also explain how maintenance steps already taken have addressed identified risks.
Standard measures set out in the guidance include:
- telemetry installation and monitoring
- proactive cleaning and maintenance programmes
- remedial capital asset improvements
- enhanced incident response arrangements
- customer engagement to reduce blockages
- power resilience and backup improvements
Firms are expected to show how their plans support Ofwat pollution incident performance commitments where applicable, while aligning short-term operational measures with longer-term Drainage and Wastewater Management Plans.
