Research and analysis

Southern Water EPA data report 2020

Updated 14 January 2022

Applies to England

This report provides company specific data and information on the Environmental Performance Assessment (EPA) metrics. It contains current year and historic performance data. For further information on what each EPA metric means see our EPA metric guide.

In addition to the EPA metrics this report contains a section on event duration monitoring (EDM) delivery. For a comparison between water companies and wider regulatory information see the Environmental performance of the water and sewerage companies in 2020 report.

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

• red - performance significantly below target
• amber - performance close to or slightly below target
• green - performance better than target

The thresholds are reviewed every 5 years.

1. EPA performance star rating

Annual performance star rating after assessment of Southern Water's performance across all EPA metrics

Year	Overall EPA star rating (out of 4)	Star rating description
2011	2 stars	Below average company
2012	2 stars	Below average company
2013	1 star	Poor performing company
2014	2 stars	Below average company
2015	3 stars	Above average company
2016	3 stars	Good company
2017	3 stars	Good company
2018	2 stars	Company requires improvement
2019	1 star	Poor performing company
2020	2 stars	Company requires improvement

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

Main facts

For 2020:

• 400 actual incidents
• 54% fewer incidents per 10,000km sewer than in 2011
• 39,139km sewer length

Annual number of pollution incidents (category 1 to 3) from Southern Water sewerage assets, with EPA rating

2011 to 2015 data

Year	2011	2012	2013	2014	2015
EPA status	red	red	red	red	amber
Incidents per 10,000km sewer	221	189	148	135	75
Actual incident numbers	479	409	320	292	163

2016 to 2020 data

Year	2016	2017	2018	2019	2020
EPA status	amber	amber	amber	red	red
Incidents per 10,000km sewer	35	31	39	110	102
Actual incident numbers	138	123	151	430	400

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

Graph note: the thresholds for a RAG status are shown in the graph background. EPA thresholds for normalised incidents (per 10,000km sewer) are shown in the EPA metric guide. They are revised every 5 years. Sewer length data was collected in 2011, then reviewed and adjusted where necessary in following years. Sewer length affects the actual number of incidents required to fall within a particular RAG status:

• green status for Southern Water was equivalent to 109 or fewer actual incidents in 2011 to 2015, 100 or fewer in 2016 and 99 or fewer in 2017 to 2020
• red status for Southern Water was equivalent to 281 or more actual incidents in 2011 to 2015, 197 or more in 2016 and 194 or more in 2017 to 2020

Number of pollution incidents (category 1 to 3) from Southern Water sewerage and clean water supply assets in 2020

Asset type	Number of pollution incidents (category 1 to 3)
Combined sewer overflow	6
Foul sewer	100
Other water industry premises	1
Pumping station	191
Rising main	29
Sewage treatment works	72
Storm tank	0
Surface water outfall	1
Water distribution system (clean)*	10
Water treatment works (clean)*	1

* Water distribution system (clean water supply) and water treatment works (clean water supply) are not part of the EPA total pollution incident (sewerage) metric.

For sewerage pollution incidents (category 1 to 3) all water companies should achieve green EPA status (for 2020 equivalent to 25 or fewer incidents per 10,000km sewer).

For 2020:

• 102 sewerage pollution incidents per 10,000km of sewer - this is rated as red
• performance was worse than the sector average (33) for sewerage pollution incidents per 10,000km of sewer
• needed 99 or fewer sewerage pollution incidents to be rated as green

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

Main facts

For 2020:

• 4 actual serious incidents
• 90% fewer serious incidents per 10,000km sewer than in 2011

Annual number of serious pollution incidents (category 1 and 2) from Southern Water sewerage assets, with EPA rating

2011 to 2015 data

Year	2011	2012	2013	2014	2015
EPA status	red	red	red	red	amber
Serious incidents per 10,000km sewer	9.7	4.6	4.2	5.5	3.2
Actual serious incident numbers	21	10	9	12	7

2016 to 2020 data

Year	2016	2017	2018	2019	2020
EPA status	amber	amber	red	red	amber
Serious incidents per 10,000km sewer	0.8	1	1.8	1.8	1.0
Actual serious incident numbers	3	4	7	7	4

Annual number of serious pollution incidents (category 1 and 2) from Southern Water sewerage assets, also showing EPA status and thresholds

Graph note: the thresholds for a RAG status are shown in the graph background. EPA thresholds for normalised incidents (per 10,000km sewer) are shown in the EPA metric guide. Sewer length data was collected in 2011, then reviewed and adjusted where necessary in following years. Sewer length affects the actual number of serious incidents required to fall within a particular RAG status:

• green status for Southern Water was equivalent to 3 or fewer actual serious incidents in 2011 to 2015 and 2 or fewer in 2016 to 2020
• red status for Southern Water was equivalent to 9 or more actual serious incidents in 2011 to 2015 and 6 or more in 2016 to 2020

Number of serious pollution incidents (category 1 and 2) from Southern Water sewerage and clean water supply assets in 2020

Asset type	Number of serious pollution incidents (category 1 and 2)
Combined sewer overflow	0
Foul sewer	2
Other water industry premises	0
Pumping station	1
Rising main	1
Sewage treatment works	0
Storm tank	0
Surface water outfall	0
Water distribution system (clean)*	0
Water treatment works (clean)*	0

* Water distribution system (clean) and water treatment works (clean) are not part of the EPA serious pollution incident (sewerage) metric.

For serious sewerage pollution incidents (category 1 and 2) all water companies should achieve green EPA status (for 2020 equivalent to 0.5 or fewer serious incidents per 10,000km sewer).

For 2020:

• 1.0 serious sewerage pollution incidents per 10,000km of sewer - this is rated as amber
• performance was worse than the sector average (0.7) for sewerage pollution incidents per 10,000km of sewer
• needed 2 or fewer actual serious sewerage pollution incidents to be rated as green

4. Discharge permit compliance metric (numeric)

Main facts

For 2020:

• 315 permitted sewage treatment works (STW)
• 25 permitted water treatment works (WTW)

Annual discharge permit compliance (numeric) for Southern Water (STW and from 2016 includes WTW), with EPA rating

2011 to 2015 data

Year	2011	2012	2013	2014	2015
EPA status	red	amber	red	green	green
Percentage permit compliance	96.0	96.8	96.0	99.0	99.3
Number of permitted STW	277	277	298	295	291
Number of non-compliant STW	11	9	12	3	2

2016 to 2020 data

Year	2016	2017	2018	2019	2020
EPA status	amber	amber	green	amber	amber
Percentage permit compliance	98.7	98.2	99.1	98.8	97.1
Number of permitted STW	293	309	313	316	315
Number of permitted WTW	11	19	20	20	25
Number of non-compliant STW	2	5	1	2	10
Number of non-compliant WTW	2	1	2	2	0

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

Graph note: the thresholds for a RAG status are shown in the graph background and in the EPA metric guide. They are revised every 5 years.

For discharge permit compliance (numeric) all water companies should achieve green EPA status (for 2020 equivalent to compliance at 99% or more of sites).

For 2020:

• 97.1% numeric discharge permit compliance - this is rated as amber
• 96.8% numeric discharge permit compliance at STW and 100% discharge permit compliance at WTW
• performance was worse than the sector average (99.2%) for numeric discharge permit compliance
• needed 3 or fewer failing sites to be rated as green
• worst performing company for numeric discharge permit compliance

5. Self-reporting of pollution incidents metric

Main facts

For 2020:

• 88% incidents self-reported
• 360 incidents self-reported
• 51 incidents reported by others

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

2011 to 2015 data

Year	2011	2012	2013	2014	2015
EPA status	green	green	green	green	amber
Percentage of incidents self-reported	84	86	77	69	59
Number of incidents self-reported	405	356	248	203	99

2016 to 2020 data

Year	2016	2017	2018	2019	2020
EPA status	amber	amber	green	green	green
Percentage of incidents self-reported	71	70	83	87	88
Number of incidents self-reported	103	94	156	400	360

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

Graph note: the thresholds for a RAG status are shown in the graph background and in the EPA metric guide. They are revised every 5 years.

Self-reporting of pollution incidents (category 1 to 3) from Southern Water sewerage and clean water supply assets in 2020

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	5	1
Foul sewer	65	35
Other water industry premises	1	0
Pumping station	182	9
Rising main	26	3
Sewage treatment works	71	1
Storm tank	0	0
Surface water outfall	0	1
Water distribution system (clean)	9	1
Water treatment works (clean)	1	0

Self-reporting of serious pollution incidents (category 1 and 2) from Southern Water sewerage and clean water supply assets in 2020

Asset type
Number of pollution incidents self-reported (category 1 and 2)	Number of pollution incidents not self-reported (category 1 and 2)
Combined sewer overflow	0	0
Foul sewer	0	2
Other water industry premises	0	0
Pumping station	0	1
Rising main	1	0
Sewage treatment works	0	0
Storm tank	0	0
Surface water outfall	0	0
Water distribution system (clean)	0	0
Water treatment works (clean)	0	0

For self-reporting of pollution incidents all water companies should achieve green EPA status (for 2020 equivalent to 75% or more of their incidents being self-reported).

For 2020:

• 88% self-reporting of pollution incidents - this is rated as green
• performance was better than the sector average (77%) for self-reporting of pollution incidents
• best performing company for self-reporting of pollution incidents

6. National Environment Programme (NEP) delivery metric

Main facts

For the financial year ending 2021:

• 34 Water Industry NEP (WINEP) schemes were completed to the planned deadline
• 5 schemes were not completed to the planned deadline

Annual delivery of the NEP (WINEP from April 2020) by Southern 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)	124	109	100	100	100
Cumulative number of schemes completed during AMP period	124	190	200	267	2

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	red	red
Percentage of NEP complete to date (cumulative)	100	100	100	90.0	87.2
Cumulative number of schemes completed during AMP period	80	113	137	207	34

Table note: 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 schemes that were completed early before their planned year were not included in the cumulative delivery percentage until their planned year (cannot report over 100%). The thresholds for each RAG status are in the EPA metric guide. They are revised every 5 years.

For NEP delivery all water companies should achieve green EPA status (for the financial year ending 2021 equivalent to 99% or more of the WINEP being delivered on time).

For the financial year ending 2021:

• 87.2% WINEP delivery - this is rated as red
• worst performing company for NEP delivery

7. Sludge disposal and use metric

Main facts

For 2020:

• 58,085t (tonnes) total volume produced (dry matter)
• 12,571ha (hectares) land used for spreading
• 98% of sludge produced was used in agriculture

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

2011 to 2015 data

Year	2011	2012	2013	2014	2015
EPA status	green	green	green	green	green
Percentage of sludge compliant	100	100	100	100	100

2016 to 2020 data

Year	2016	2017	2018	2019	2020
EPA status	green	green	N/A	N/A	N/A
Percentage of sludge compliant	100	100	N/A	N/A	N/A

Table note: from the 2018 calendar year, we suspended the metric from the EPA whilst we reviewed our regulatory regime for sludge. The thresholds for each RAG status are in the EPA metric guide. They are revised every 5 years.

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

Year	Sewage sludge used in agriculture (t thousands)	Sewage sludge recovered non-agriculture (t thousands)	Sewage sludge disposed (t thousands)	Actual quantity produced (t thousands)
2011	101.1	0.0	0.3	101.4
2012	59.5	0.0	0.0	59.5
2013	63.8	0.0	0.2	64.0
2014	61.0	0.0	0.0	61.0
2015	50.9	0.0	0.0	50.9
2016	60.4	0.0	0.0	60.4
2017	53.2	0.0	0.0	53.2
2018	53.8	0.0	0.0	53.8
2019	50.7	0.0	0.0	50.7
2020	57.1	1.0	0.0	58.1

8. Security of Supply Index (SoSI) metric

Main facts

For the financial year ending 2021:

• 14 water resource zones
• 563 Ml/d water distributed to the network (megalitres)

Annual compliance with SoSI by Southern Water, with EPA ratings

Financial year ending	2017	2018	2019	2020	2021
EPA status	green	green	red	green	green
SoSI score	100	100	98	100	100

Table note : the thresholds for each RAG status are in the EPA metric guide.

For SoSI all water companies should achieve green EPA status (for the financial year ending 2021 equivalent to a SoSI of 100).

For the financial year ending 2021:

• score 100 - this is rated as green

9. Event Duration Monitoring (EDM) delivery

All water companies have investment in place to monitor the vast majority of storm overflows. Installation of EDM monitors is mostly funded through the WINEP however does not form part of the EPA WINEP delivery metric. We have published the EDM dataset from the water companies describing how often and for how long the monitored storm overflows operated during 2020. All water companies have also published their EDM data returns and supporting commentaries.

Southern Water storm overflows

Year	2020
Total number of storm overflows	975
Number of storm overflows with annual data reported	945
Percentage of storm overflows with annual data reported	97
Average number of spills per storm overflow	21
Average duration of spill (hours)	10