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This publication is available at https://www.gov.uk/government/publications/water-and-sewerage-companies-in-england-environmental-performance-report-2023/south-west-water-epa-data-report-2023
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 2023 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 2023:
red status for 2 metrics, amber status for 2 metrics and green status for 3 metrics
1 of 5 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
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
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 and 2023.
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
2. Total pollution incidents (sewerage) metric (category 1 to 3)
Main facts
For 2023:
111 sewerage pollution incidents per 10,000km of sewer – this is rated as red
194 actual incidents (needed 37 or fewer to be rated as green)
17,440km sewer length
performance was worse than the sector (36) for sewerage pollution incidents per 10,000km of sewer
worst performing company for this EPA metric and 1 of 3 companies (out of 9) to be rated red, no companies rated green
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
no data
no data
Incidents per 10,000km sewer
87
62
111
no data
no data
Actual incident numbers
151
108
194
no data
no 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
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
61 or above
35 to 60
34 or below
Number of pollution incidents (total category 1 to 3) from South West Water sewerage and water supply assets in 2023
Asset type
Number of pollution incidents (category 1 to 3)
Combined sewer overflow
13
Foul sewer
40
Other water industry premises
2
Pumping station
71
Rising main
13
Sewage treatment works
54
Storm tank
0
Surface water outfall
1
Water distribution system (water supply)
27
Water treatment works (water supply)
2
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 2023
Asset type
Category 1 to 3
Category 1
Category 2
Category 3
Combined sewer overflow
13
0
0
13
Foul sewer
40
0
0
40
Other water industry premises
2
0
0
2
Pumping station
71
0
0
71
Rising main
13
0
1
12
Sewage treatment works
54
0
1
53
Storm tank
0
0
0
0
Surface water outfall
1
0
0
1
Water distribution system (water supply)
27
0
0
27
Water treatment works (water supply)
2
0
0
2
3. Serious pollution incidents (sewerage and water supply) metric (category 1 and 2)
Main facts
For 2023:
2 serious incidents – this is rated as amber (needed 1 or 0 to be rated as green)
2 serious incidents from sewerage assets
0 serious incidents from water supply assets
1 of 5 companies (out of 9) to not be 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
no data
no data
Serious incident numbers – all assets
8
2
2
no data
no data
Serious incident numbers – sewerage
8
2
2
no data
no data
Serious incident numbers – water supply
0
0
0
no data
no 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
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 2023
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
1
Sewage treatment works
1
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 2023:
82% of all incidents self-reported, 93% from just pumping stations (PS) and sewage treatment works (STW) combined – this is rated as green
182 self-reported incidents, 41 incidents reported by others
performance was worse than the sector (84%) for self-reporting of all pollution incidents
performance was the same as the sector average (93%) for self-reporting of just PS and STW pollution incidents combined
1 of 6 companies (out of 9) to 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
no data
no data
Percentage of incidents self-reported
68
78
82
no data
no data
Number of incidents self-reported
108
106
182
no data
no data
Percentage of PS and STW incidents self-reported
84
87
93
no data
no data
Number of PS and STW incidents self-reported
64
40
116
no data
no 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 2023
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
9
4
Foul sewer
23
17
Other water industry premises
2
0
Pumping station
66
5
Rising main
12
1
Sewage treatment works
50
4
Storm tank
0
0
Surface water outfall
0
1
Water distribution system (water supply)
19
8
Water treatment works (water supply)
1
1
Self-reporting of serious pollution incidents (category 1 to 2) from South West Water sewerage and water supply assets in 2023
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
1
0
Sewage treatment works
1
0
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 2023:
96.2% numeric discharge permit compliance – this is rated as red
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
worst performing company for this metric and only company (out of 9) to be rated red
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
no data
no data
Percentage permit compliance
97.5
99.4
96.2
no data
no data
Number of permitted discharge outlets from STW
305
305
305
no data
no data
Number of permitted discharge outlets from WTW
10
10
10
no data
no data
Number of non-compliant STW
6
2
11
no data
no data
Percentage compliance STW
98.0
99.3
96.4
no data
no data
Number of non-compliant WTW
2
0
1
no data
no data
Percentage compliance WTW
80.0
100
90.0
no data
no 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 2024 (cumulative progress years 1 to 4 of the WINEP):
98.8% EPA schemes completed within planned deadlines – this is rated as amber (needed 100% to be rated as green)
419 EPA schemes completed within planned deadlines
5 EPA schemes (all water quality) did not meet requirements within planned deadline
performance was worse than the sector (99.2%)
1 of 3 companies (out of 9) not to be rated green
all 554 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
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 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
no data
no data
Percentage of WINEP complete within deadlines (to date)
96.8
99.5
98.8
no data
no data
Cumulative number of schemes completed during AMP period
276
374
419
no data
no data
Cumulative number of water quality schemes completed during AMP period
239
322
363
no data
no data
Cumulative number of water resources schemes completed during AMP period
3
5
8
no data
no data
Cumulative number of fisheries, biodiversity and geomorphology schemes completed during AMP period
34
47
48
no data
no data
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 2023:
99.77% satisfactory sludge disposal and use – this is rated as green
43,748t (tonnes dry solid) total volume dispatched
7,161ha (hectares) land used for spreading
90.6% of sludge produced was used in agriculture
1 of 4 companies (out of 9) to report less than 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
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
no data
no data
Percentage of sludge compliant
no data
99.14
99.77
no data
no data
Total volume of sludge dispatched (t thousands dry solid)
45.6
47.2
43.7
no data
no 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
637 megalitres per day water distributed into the network – above forecast
1 of 9 companies (out of 9) to be rated green
Annual compliance with SDBI by South West Water, with EPA ratings
Financial year ending
2022
2023
2024
2025
2026
EPA status
red
red
green
no data
no data
SDBI score
93
86
100
no data
no data
Table note: the EPA RAG status thresholds are in the EPA metric guide. The SDBI score for financial year ending 2022 is different to the score of less than 99 published in July 2022. 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 2023. The 2023 dataset also includes water company reasons for performance issues with monitors and reasons for high spill counts.
South West Water storm overflows
Year
2023
Total number of active storm overflows listed in the annual return
1,356
Total number of active storm overflows with EDM commissioned
1,356
Percentage of active storm overflows listed with EDM commissioned
100
Total number of storm overflows with spill data
1,342
Percentage of storm overflows listed with spill data
97.7
Average number of spills per storm overflow with spill data
43.4
Average duration (hours) per monitored spill event
9.1
Percentage storm overflows with ≥90% EDM operation during reporting period
