South West Water EPA data report 2024

This report provides company specific data and information on the Environmental Performance Assessment (EPA) metrics. It contains current year and historic performance data (as published at the time, based on data provided in part by the water companies). For further information on what each EPA metric and performance star ratings mean see our EPA metric guide.

In addition to the EPA metrics, this report contains a section on event duration monitoring (EDM) of storm overflows. For a comparison between water companies and wider regulatory information see the Environmental performance of the water and sewerage companies in 2024 report.

We set targets for each EPA metric. Company performance is then given a red, amber or green (RAG) status:

• red – significantly below target
• amber – below target
• green – achieved target or better

We review and revise thresholds every 5 years.

1. EPA metric status and performance star rating

Main facts

For 2024:

• red status for 2 metrics, amber status for 3 metrics and green status for 2 metrics
• 1 of 7 companies (out of 9) rated as requires improvement (2 stars)

Annual performance star rating after assessment of South West Water’s performance across all EPA metrics

Annual percentage of red, amber or green (RAG) status EPA metric results for South West Water

Graph note: there were 6 EPA metrics in the years 2011 to 2015 and 2018 to 2021. There were 7 EPA metrics in the years 2016, 2017, 2022, 2023 and 2024.

Annual number of EPA metrics and their RAG status results for South West Water

2. Total pollution incidents (sewerage) metric (category 1 to 3)

Main facts

For 2024:

• 108 sewerage pollution incidents per 10,000km of sewer – this is rated as red
• 189 actual incidents (needed 35 or fewer to be rated as green)
• 17,440km sewer length – from financial year ending 2018 (this baseline is used in the EPA)
• performance was worse than the sector (47) for sewerage pollution incidents per 10,000km of sewer
• 1 of 7 companies (out of 9) to be rated red, no companies rated green
• worst performing company for this EPA metric – the same as 2023

Annual number of pollution incidents (category 1 to 3) from South West Water sewerage assets, with EPA status

2011 to 2015 data

2016 to 2020 data

2021 to 2025 data

Annual number of pollution incidents (category 1 to 3) from South West Water sewerage assets, also showing EPA status and thresholds

Graph note: the EPA RAG status thresholds are set for normalised (per 10,000km sewer) numbers of sewerage incidents (see our EPA metric guide). We review and revise thresholds every 5 years. Equivalent thresholds for actual incident numbers are calculated using water company sewer length data – these are shown in the graph background and the table below.

EPA thresholds for actual number of South West Water sewerage incidents for the calendar years 2011 to 2025

Number of pollution incidents (category 1 to 3) from South West Water sewerage and water supply assets in 2024

Note: water distribution system and water treatment works (both water supply assets) are not part of the EPA total pollution incidents (sewerage) metric.

Number of pollution incidents (total and breakdown of categories 1 to 3) from South West Water sewerage and water supply assets in 2024

3. Serious pollution incidents (sewerage and water supply) metric (category 1 and 2)

Main facts

For 2024:

• 4 serious incidents – this is rated as red (needed 1 or 0 to be rated as green)
• 4 serious incidents from sewerage assets
• 0 serious incidents from water supply assets
• 1 of 5 companies (out of 9) to be rated red

Annual number of serious pollution incidents (category 1 and 2) from South West Water assets (sewerage and from 2021 including water supply), with EPA status

2011 to 2015 data

2016 to 2020 data

2021 to 2025 data

Annual number of serious pollution incidents (category 1 and 2) from South West Water assets (sewerage and from 2021 including water supply), also showing EPA status and thresholds

Graph note: for 2011 to 2020 EPA RAG status thresholds were set for normalised (per 10,000km sewer) numbers of serious sewerage incidents (see our EPA metric guide). Equivalent thresholds for actual serious sewerage incident numbers were calculated using water company sewer length data. We review and revise thresholds every 5 years. For 2021 to 2025 water companies are in one of two groups with different thresholds set for actual serious sewerage and water supply incident numbers. The thresholds for actual serious incident numbers are shown in the graph background and the table below.

EPA thresholds for number of serious incidents from South West Water assets (sewerage and from 2021 including water supply) for the calendar years 2011 to 2025

Number of serious pollution incidents (category 1 and 2) from South West Water sewerage and water supply assets in 2024

4. Self-reporting of pollution incidents (sewerage and water supply) metric

Main facts

For 2024:

• 82% of all incidents self-reported, 89% from just pumping stations (PS) and sewage treatment works (STW) combined – this is rated as amber
• needed 80% or higher self-reporting and 90% from just PS and STW combined to be rated as green
• 171 self-reported incidents, 38 incidents reported by others
• performance was worse than the sector (85%) for self-reporting of all pollution incidents
• performance was worse than the sector (92%) for self-reporting of just PS and STW pollution incidents combined
• 1 of 4 companies (out of 9) to not be rated green

Annual self-reporting of pollution incidents (category 1 to 3) from South West Water sewerage and water supply assets, with EPA rating

2011 to 2015 data

2016 to 2020 data

2021 to 2025 data

Annual self-reporting of pollution incidents (category 1 to 3) from South West Water sewerage and water supply assets, also showing EPA status and thresholds

Graph note: the EPA RAG status thresholds (for all sewerage and water supply assets) are shown in the graph background and in the EPA metric guide. We review and revise thresholds every 5 years. From 2021 the additional number in brackets is the self-reporting percentage for just PS and STW incidents combined. To achieve green status self-reporting for all assets must be 80% or above and for just STW and PS combined must be 90% or above.

Self-reporting of pollution incidents (category 1 to 3) from South West Water sewerage and water supply assets in 2024

Self-reporting of serious pollution incidents (category 1 to 2) from South West Water sewerage and water supply assets in 2024

5. Discharge permit compliance (numeric) metric

Main facts

For 2024:

• 98.1% numeric discharge permit compliance – this is rated as amber
• 305 permitted discharge outlets from STW – 98.4% compliance (5 non-compliant STW)
• 10 permitted discharge outlets from water treatment works (WTW) – 90.0% compliance (1 non-compliant WTW)
• needed 3 or fewer non-compliant treatment works to be rated as green
• performance was worse than the sector (98.8%) for numeric discharge permit compliance
• 1 of 5 companies (out of 9) to be rated amber

Annual discharge permit compliance (numeric) for South West Water (STW and from 2016 includes WTW), with EPA status

2011 to 2015 data

2016 to 2020 data

2021 to 2025 data

Annual discharge permit compliance (numeric) for South West Water (STW and from 2016 includes WTW), also showing EPA status and thresholds

Graph note: the EPA RAG status thresholds are shown in the graph background and in the EPA metric guide. We review and revise thresholds every 5 years.

6. Delivery of the Water Industry National Environment Programme (WINEP) metric

Main facts

For the financial year ending 2025 (cumulative progress years 1 to 4 of the WINEP):

• 98.3% EPA schemes completed within planned deadlines – this is rated as amber (needed 100% to be rated as green)
• 531 EPA schemes completed within planned deadlines
• 9 EPA schemes did not meet requirements within planned deadlines – 8 water quality and 1 water resources
• performance was better than the sector (97.0%)
• 1 of 6 companies (out of 9) to not be rated green
• 559 non-EPA WINEP schemes completed within planned deadlines

Annual delivery of the NEP (WINEP from April 2020) by South West Water, with EPA rating

Data for financial years ending 2012 to 2016

Data for financial years ending 2017 to 2021

Data for financial years ending 2022 to 2026

Table note 1: AMP5 schemes that were completed early before their planned year were included in the cumulative delivery percentage (in some cases resulting in percentages over 100%). AMP6 and AMP7 schemes that were completed early before their planned year are not included in the cumulative delivery percentage until their planned year (cannot report over 100%). The EPA RAG status thresholds are in the EPA metric guide. We review and revise thresholds every 5 years.

Table note 2: the WINEP EPA metric data for financial years ending 2022 and 2023 is different to the EPA metric data published in July 2022 and July 2023. This is as a result of subsequent audits and checking.

7. Sludge disposal and use metric

Main facts

For 2024:

• 100% satisfactory sludge disposal and use – this is rated as green
• 45,514t (tonnes dry solid) total volume dispatched
• 7,047ha (hectares) land used for spreading
• 87.79% of sludge produced was used in agriculture
• 1 of 6 companies (out of 9) to report 100% satisfactory sludge disposal and use – all companies rated green

Annual compliance with sludge disposal and use metric by South West Water, with EPA ratings

2011 to 2015 data

2016 to 2020 data

2021 to 2025 data

Table note: for the 2018 to 2021 calendar years, we suspended the metric from the EPA whilst we reviewed our regulatory regime for sludge. The EPA RAG status thresholds are in the EPA metric guide.

Annual summary of sewage sludge disposal and use (dry matter) by South West Water

8. Supply Demand Balance Index (SDBI) metric

Main facts

For the financial year ending 2025:

• SDBI of 100 – this is rated as green
• 4 water resource zones
• 633.82 megalitres per day water distributed into the network – above forecast
• 1 of 8 companies (out of 9) to be rated green

Annual compliance with SDBI by South West Water, with EPA ratings

Table note: the EPA RAG status thresholds are in the EPA metric guide. The SDBI score for financial year ending 2024 is different to the score of less than 99 published in July 2024. This is as a result of subsequent audits and checking.

9. Event Duration Monitoring (EDM) delivery

We have published the EDM storm overflow annual return dataset received from water companies. This shows how often and how long the monitored storm overflows operated during 2024. The 2024 dataset also includes water company reasons for performance issues with monitors and reasons for high spill counts.

South West Water storm overflows