Guidance

8. Forward look and future reporting

Published 15 October 2025

Applies to England and Wales

• Publication for Northern Ireland
• Publication for Scotland

8.1 Ongoing performance reporting role

Water and sewerage companies should perform in line with statutory obligations and Water Industry Strategic Environmental Requirements (WISER). We will continue to regulate in a fair and transparent way, and we will:

• use the current Environmental Performance Assessment (EPA) in the annual performance review meetings between the Environment Agency and water and sewerage company chief executive officers (CEOs)
• publish the ‘Environmental Performance of the water and sewerage companies in England’ report, annually
• continue ongoing development of the EPA for 2026 to 2030 and we will review the EPA for the next 5 year period covering data for 2031 to 2035 (section 8.2)
• continue to work with other bodies on performance measurement and assessment, for example Ofwat, Consumer Council for Water (CCW) and Drinking Water Inspectorate as appropriate
• feed into a single report under a new regulator when required
• ensure our updated metrics align with recommendations made by Sir John Cunliffe and the Independent Water Commission (IWC) to provide a wider view of water company environmental impacts as well as improved transparency and confidence
• continue data sharing with Water UK for the Discover Water website, Environment Agency liaison with the Department for Environment, Food and Rural Affairs (Defra) and Natural Resources Wales liaison with the Welsh Government are ongoing

8.2 Ongoing EPA development

Our development of the EPA and reporting for 2026 to 2030 continues and it is our intention that the shadow metrics in section 7 progress to become live.

EPA review for 2031 to 2035

We will review the EPA again for the next 5 year period covering data for 2031 to 2035. We intend to add dry weather flow (DWF) compliance to FFT compliance as a wider flow metric – the definition for DWF has already been developed (section 8.3). We intend to develop the storm overflow metric to focus on spill frequency or environmental impact.

We will look at options to revise other current EPA metrics. We will also review the development of new EPA metrics or add additional narratives. This may include waste management licence compliance, flood resilience, phosphorus reduction and reasons for not achieving good status to support delivery of the Water Framework Directive.

8.3 Waste water treatment works dry weather flow (DWF) annual numeric permit limit compliance

Background

Alongside the waste water treatment works (WWTW) flow to full treatment (FFT) shadow metric (section 7.2), there will be a DWF shadow assessment. The definition for this has been developed. However, not all WWTW will have the permit condition in place for sufficient time to enable the full 4 year ‘look-back’ period prior to 2026 (the 3 in 5 methodology). We will therefore shadow assess DWF compliance from 2026. Our intention is to add this to the live FFT metric to be a broader flow metric for 2031 data onwards. The shadow DWF part of the flow metric definition is set out in this section.

Definition of metric

From the 2026 data year (starting 1 January 2026) we assess WWTW compliance with DWF numeric limits, using total daily volumes (TDVs) from a calendar year. A WWTW fails where the limit is exceeded in the current calendar year and there have been 2 or more exceedances in the preceding 4 calendar years.

DWF is the average daily flow to a WWTW during a period without rainfall. DWF, aligned with the discharge quality limits, allow us to control the load of pollutants discharged to the environment from a WWTW.

We assess compliance with the permitted DWF limit annually following the submission of TDV data from the water and sewerage companies. This is required to be submitted by the end of February for the previous year’s data.

The DWF permit limit is set at the measured or predicted Q80 flow (flow value exceeded 80% of the time). However, we assess compliance against the permitted DWF limit using calendar year calculated Q90 flow (flow value exceeded 90% of the time) not the Q80. This is to allow for year-on-year variability in catchment flow rates and uncertainty when measuring the daily volumes. If compliance was assessed against the Q80 value, then in a year when rainfall is significantly above average, the measured Q80 would be higher than normal. This would make it possible that a non-compliance would be recorded for reasons outside of the operator’s control.

Where the Q90 value is greater than the DWF limit then there has been a DWF limit exceedance. From 2026, we will assess WWTW compliance with DWF limits for each calendar year. Fails will be where a limit is exceeded in the year being assessed and there have been 2 or more exceedances in the preceding 4 years (following the 3 in 5 year methodology).

Obligation      

This metric is relevant to the Environmental Permitting (England & Wales) Regulations 2016 and the Urban Waste Water Treatment (England & Wales) Regulations 1994.

Calculation

The calculation for percentage compliance is (B – A) ÷ B × 100 where:

• A is the number of WWTW failing the 3 in 5 year dry weather flow assessment – that is where the permitted limit is exceeded in the assessment year and 2 or more of the preceding 4 years
• B is the number of WWTW with dry weather flow permit limits on the Environment Agency or Natural Resources Wales register during the calendar year

The calculation result is rounded to 1 decimal place for assessment against the thresholds that we are developing and for reporting.

Frequency of assessment

This shadow metric is assessed annually based on a calendar year. The reporting year is 1 January to 31 December each year. We intend to add this assessment to the live FFT metric to be a broader flow metric for 2031 data onwards.

Expectation

In 2022 the Environment Agency set out its performance expectations for 2025 to 2030 in the WISER. The WISER performance expectation is 100% compliance with flow permit conditions. This will inform the EPA RAG status thresholds that we set when the metric is live.

RAG status thresholds

There are no RAG status thresholds at this stage of the shadow metric. Data assessment during the shadow metric period will inform our development of RAG status thresholds for this metric.

Next: go to Appendix 1: Numeric rating scenario tables on the publication page.