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This publication is available at https://www.gov.uk/government/publications/water-and-sewerage-companies-in-england-environmental-performance-report-2025/south-west-water-epa-data-report-2025
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 and sewerage 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 and sewerage companies and wider regulatory information see the environmental performance of the water and sewerage companies in 2025 report.
We set targets for each EPA metric. Water and sewerage company performance is then given a red, amber or green (RAG) status:
red – significantly below target
amber – below target
green – achieved target
We review and revise thresholds every 5 years.
1. EPA metric status and performance star rating
Main facts
For 2025:
red status for 3 metrics, amber status for 2 metric and green status for 1 metrics
1 of 4 water and sewerage companies (out of 9) rated as poor performing (1 stars)
Annual performance star rating after assessment of South West Water’s performance across all EPA metrics
Year
Overall EPA star rating (out of 4)
Star rating description
2011
1 star
Poor performing company
2012
2 stars
Below average company
2013
1 star
Poor performing company
2014
2 stars
Below average company
2015
1 star
Poor performing company
2016
2 stars
Company requires improvement
2017
2 stars
Company requires improvement
2018
2 stars
Company requires improvement
2019
2 stars
Company requires improvement
2020
2 stars
Company requires improvement
2021
1 star
Poor performing company
2022
2 stars
Company requires improvement
2023
2 stars
Company requires improvement
2024
2 stars
Company requires improvement
2025
1 star
Poor performing company
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, 2018 to 2021, and 2025. 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
Year
Number of metrics in EPA
Number of red metrics
Number of amber metrics
Number of green metrics
2011
6
4
0
2
2012
6
2
2
2
2013
6
3
1
2
2014
6
1
3
2
2015
6
3
2
1
2016
7
2
3
2
2017
7
2
2
3
2018
6
1
2
3
2019
6
1
3
2
2020
6
2
2
2
2021
6
5
1
0
2022
7
2
3
2
2023
7
2
2
3
2024
7
2
3
2
2025
6
3
2
1
2. Total pollution incidents (sewerage) metric (category 1 to 3)
Main facts
For 2025:
51 sewerage pollution incidents per 10,000km of sewer – this is rated as red
124 actual incidents (needed 47 or fewer to be rated as green)
24,215km sewer length – Sewer length was agreed before the start of the EPA period
performance was worse than the sector (41) for sewerage pollution incidents per 10,000km of sewer
1 of 8 water and sewerage companies (out of 9) to be rated red
Annual number of pollution incidents (category 1 to 3) from South West Water sewerage assets, with EPA status
2011 to 2015 data
Year
2011
2012
2013
2014
2015
EPA status
red
red
red
red
red
Incidents per 10,000km sewer
159
223
267
169
171
Actual incident numbers
147
206
246
156
158
2016 to 2020 data
Year
2016
2017
2018
2019
2020
EPA status
red
red
red
red
red
Incidents per 10,000km sewer
115
109
98
105
131
Actual incident numbers
179
169
168
180
225
2021 to 2025 data
Year
2021
2022
2023
2024
2025
EPA status
red
red
red
red
red
Incidents per 10,000km sewer
87
62
111
108
51
Actual incident numbers
151
108
194
189
124
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
Calendar year
Red status
Amber status
Green status
2011 to 2015
120 or above
47 to 119
46 or below
2016 and 2017
78 or above
40 to 77
39 or below
2018 to 2020
86 or above
44 to 85
43 or below
2021
73 or above
41 to 72
40 or below
2022
69 or above
40 to 68
39 or below
2023
66 or above
38 to 65
37 or below
2024
64 or above
36 to 63
35 or below
2025
84 or above
48 to 83
47 or below
Number of pollution incidents (category 1 to 3) from South West Water sewerage and water supply assets in 2025
Asset type
Number of pollution incidents (category 1 to 3)
Combined sewer overflow
5
Foul sewer
23
Other water industry premises
1
Pumping station
39
Rising main
7
Sewage treatment works
40
Storm tank
0
Surface water outfall
9
Water distribution system (water supply)
13
Water treatment works (water supply)
0
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 2025
Asset type
Category 1 to 3
Category 1
Category 2
Category 3
Combined sewer overflow
5
0
0
5
Foul sewer
23
0
0
23
Other water industry premises
1
0
0
1
Pumping station
39
0
0
39
Rising main
7
0
0
7
Sewage treatment works
40
1
2
37
Storm tank
0
0
0
0
Surface water outfall
9
0
0
9
Water distribution system (water supply)
13
0
0
13
Water treatment works (water supply)
0
0
0
0
3. Serious pollution incidents (sewerage and water supply) metric (category 1 and 2)
Main facts
For 2025:
3 serious incidents – this is rated as red (needed 0 to be rated as green)
3 serious incidents from sewerage assets
0 serious incidents from water supply assets
1 of 7 water and sewerage companies (out of 9) to be rated red, no companies rated green
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
Year
2011
2012
2013
2014
2015
EPA status
red
red
red
amber
red
Serious incidents per 10,000km sewer
18.4
4.3
10.8
3.3
7.6
Actual serious incident numbers – sewerage
17
4
10
3
7
2016 to 2020 data
Year
2016
2017
2018
2019
2020
EPA status
red
red
amber
amber
red
Serious incidents per 10,000km sewer
2.6
1.9
1.2
0.6
1.7
Actual serious incident numbers – sewerage
4
3
2
1
3
2021 to 2025 data
Year
2021
2022
2023
2024
2025
EPA status
red
amber
amber
red
red
Serious incident numbers – all assets
8
2
2
4
3
Serious incident numbers – sewerage
8
2
2
4
3
Serious incident numbers – water supply
0
0
0
0
0
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
Calendar year
Red status
Amber status
Green status
2011 to 2015
4 or above
2 or 3
1 or 0
2016 to 2020
3 or above
1 or 2
0
2021 and 2022
4 or above
2 or 3
1 or 0
2023 and 2024
3 or above
2
1 or 0
2025
2 or above
1
0
Number of serious pollution incidents (category 1 and 2) from South West Water sewerage and water supply assets in 2025
Asset type
Number of serious pollution incidents (category 1 and 2)
Combined sewer overflow
0
Foul sewer
0
Other water industry premises
0
Pumping station
0
Rising main
0
Sewage treatment works
3
Storm tank
0
Surface water outfall
0
Water distribution system (water supply)
0
Water treatment works (water supply)
0
4. Self-reporting of pollution incidents (sewerage and water supply) metric
Main facts
For 2025:
71% of all incidents self-reported, 77% from just pumping stations (PS) and sewage treatment works (STW) combined – this is rated as amber
97 self-reported incidents, 40 incidents reported by others
performance was worse than the sector (87%) for self-reporting of all pollution incidents
performance was worse than the sector (93%) for self-reporting of just PS and STW pollution incidents combined
only water and sewerage 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
Year
2011
2012
2013
2014
2015
EPA status
red
amber
amber
amber
amber
Percentage of incidents self-reported
24
41
55
42
48
Number of incidents self-reported
36
85
137
66
79
2016 to 2020 data
Year
2016
2017
2018
2019
2020
EPA status
amber
amber
green
green
amber
Percentage of incidents self-reported
64
68
77
76
74
Number of incidents self-reported
119
123
133
141
175
2021 to 2025 data
Year
2021
2022
2023
2024
2025
EPA status
amber
amber
green
amber
amber
Percentage of incidents self-reported
68
78
82
82
71
Number of incidents self-reported
108
106
182
171
97
Percentage of PS and STW incidents self-reported
84
87
93
89
77
Number of PS and STW incidents self-reported
64
40
116
109
61
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 2025
Asset type
Number of pollution incidents self-reported (category 1 to 3)
Number of pollution incidents not self-reported (category 1 to 3)
Combined sewer overflow
4
1
Foul sewer
11
12
Other water industry premises
1
0
Pumping station
30
9
Rising main
6
1
Sewage treatment works
31
9
Storm tank
0
0
Surface water outfall
3
6
Water distribution system (water supply)
11
2
Water treatment works (water supply)
0
0
Self-reporting of serious pollution incidents (category 1 to 2) from South West Water sewerage and water supply assets in 2025
Asset type
Number of serious pollution incidents self-reported (category 1 to 2)
Number of serious pollution incidents not self-reported (category 1 to 2)
Combined sewer overflow
0
0
Foul sewer
0
0
Other water industry premises
0
0
Pumping station
0
0
Rising main
0
0
Sewage treatment works
2
1
Storm tank
0
0
Surface water outfall
0
0
Water distribution system (water supply)
0
0
Water treatment works (water supply)
0
0
5. Discharge permit compliance (numeric) metric
Main facts
For 2025:
98.1% numeric discharge permit compliance – this is rated as amber (needed 3 or fewer non-complaint treatment works to be rated as green)
11 permitted discharge outlets from water treatment works (WTW) – 100% compliance (0 non-compliant WTW)
performance was better than the sector (97.4%) for numeric discharge permit compliance
1 of 5 water and sewerage 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
Year
2011
2012
2013
2014
2015
EPA status
red
amber
red
amber
red
Percentage permit compliance
90.1
97.1
92.5
96.1
95.8
Number of permitted discharge outlets from STW
304
307
306
305
307
Number of non-compliant STW
30
9
23
12
13
2016 to 2020 data
Year
2016
2017
2018
2019
2020
EPA status
amber
amber
amber
amber
green
Percentage permit compliance
98.1
97.1
98.7
98.7
99.0
Number of permitted discharge outlets from STW
306
304
307
305
305
Number of permitted discharge outlets from WTW
6
6
6
6
6
Number of non-compliant STW
5
9
4
4
2
Number of non-compliant WTW
1
0
0
0
1
2021 to 2025 data
Year
2021
2022
2023
2024
2025
EPA status
red
green
red
amber
amber
Percentage permit compliance
97.5
99.4
96.2
98.1
98.1
Number of permitted discharge outlets from STW
305
305
305
305
305
Number of permitted discharge outlets from WTW
10
10
10
10
11
Number of non-compliant STW
6
2
11
5
6
Percentage compliance STW
98.0
99.3
96.4
98.4
98.0
Number of non-compliant WTW
2
0
1
1
0
Percentage compliance WTW
80.0
100
90.0
90.0
100
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 March 2026 (cumulative progress years 1 to 5 of the WINEP):
94.2% EPA schemes completed within planned deadlines – this is rated as red (needed 100% to be rated as green)
65 EPA schemes completed within planned deadlines
4 EPA schemes did not meet requirements within planned deadlines – 4 water resources
performance was better than the sector (80.2%)
1 of 4 companies (out of 9) to be rated red
0 non-EPA WINEP schemes completed out of 0 planned – 94.2% total WINEP delivery (EPA and non-EPA schemes)
Annual delivery of the WINEP (National Environment Programme up to the financial year ending 2020) by South West Water, with EPA rating
Data for financial years ending 2012 to 2016
Financial year ending
2012
2013
2014
2015
2016
Asset Management Plan (AMP)
AMP5
AMP5
AMP5
AMP5
AMP6
EPA status
green
green
green
green
green
Percentage of NEP complete to date (cumulative)
859
102
101
100
100
Cumulative number of schemes completed during AMP period
275
315
319
367
1
Data for financial years ending 2017 to 2021
Financial year ending
2017
2018
2019
2020
2021
Asset Management Plan (AMP)
AMP6
AMP6
AMP6
AMP6
AMP7
EPA status
green
green
green
amber
green
Percentage of NEP/WINEP complete to date (cumulative)
100
100
100
97.4
100
Cumulative number of schemes completed during AMP period
29
78
110
149
68
Data for financial years ending 2022 to 2026
Financial year ending
2022
2023
2024
2025
2026
Asset Management Plan (AMP)
AMP7
AMP7
AMP7
AMP7
AMP8
EPA status
red
amber
amber
amber
red
Percentage of WINEP complete within deadlines (to date)
96.8
99.5
98.8
98.3
94.2
Cumulative number of schemes completed during AMP period
276
374
419
531
65
Cumulative number of water quality schemes completed during AMP period
239
322
363
453
60
Cumulative number of water resources schemes completed during AMP period
3
5
8
9
4
Cumulative number of fisheries, biodiversity and geomorphology schemes completed during AMP period
34
47
48
69
1
Annual delivery of the WINEP (National Environment Programme up to the financial year ending 2020) by South West Water, also showing EPA status and thresholds
Table and graph 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 and graph note 2: the WINEP EPA metric data for the financial years ending 2022 and 2023 are different to the EPA metric data published at the time. This is as a result of subsequent audits and checking.
7. Sludge disposal and use metric
Main facts
100% satisfactory sludge disposal and use – this is rated as green
47,351t (tonnes dry solid) total volume dispatched
6,740ha (hectares) land used by them for spreading
92.05% of sludge dispatched was used by them in agriculture
1 of 8 water and sewerage companies (out of 9) to report 100% satisfactory sludge disposal and use – all water and sewerage companies rated green
Annual compliance with sludge disposal and use metric by South West Water, with EPA ratings
2011 to 2015 data
Year
2011
2012
2013
2014
2015
EPA status
green
green
green
green
amber
Percentage of sludge compliant
100
100
100
100
99.98
Total volume of sludge dispatched (t thousands dry solid)
70.3
66.9
46.7
43.4
42.2
2016 to 2020 data
Year
2016
2017
2018
2019
2020
EPA status
amber
green
no data
no data
no data
Percentage of sludge compliant
99.97
100
no data
no data
no data
Total volume of sludge dispatched (t thousands dry solid)
43.6
39.1
44.4
34.5
43.7
2021 to 2025 data
Year
2021
2022
2023
2024
2025
EPA status
no data
green
green
green
green
Percentage of sludge compliant
no data
99.14
99.77
100
100
Total volume of sludge dispatched (t thousands dry solid)
45.6
47.2
43.7
45.5
47.4
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
Year
Sewage sludge used by them in agriculture (t thousands)
Sewage sludge recovered by them non-agriculture (t thousands)
Sewage sludge disposed of by them or passed to other outlets(t thousands)
2021
43.7
1.7
0.2
2022
45.9
1.0
0.3
2023
39.7
3.6
0.5
2024
40.0
5.2
0.3
2025
43.6
3.6
0.2
8. Event Duration Monitoring (EDM) delivery
We have published the EDM storm overflow annual return dataset received from water and sewerage companies. This shows how often and how long the monitored storm overflows operated during 2025. The dataset also includes water and sewerage company reasons for performance issues with monitors and reasons for high spill counts.
South West Water storm overflows
Year
2025
Total number of active storm overflows listed in the annual return
1,358
Total number of active storm overflows with EDM commissioned
1,358
Percentage of active storm overflows listed with EDM commissioned
100%
Total number of storm overflows with spill data
1,357
Percentage of storm overflows listed with spill data
100%
Average number of spills per storm overflow with spill data
34.0
Average duration (hours) per monitored spill event
8.8
Percentage storm overflows with ≥90% EDM operation during reporting period
