Thames Water EPA data report 2020
Updated 14 January 2022
Applies to England
© Crown copyright 2022
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This publication is available at https://www.gov.uk/government/publications/water-and-sewerage-companies-in-england-environmental-performance-report-2020/thames-water-epa-data-report-2020
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 Thames Water’s performance across all EPA metrics
| Year | Overall EPA star rating (out of 4) | Star rating description |
|---|---|---|
| 2011 | 3 stars | Above average company |
| 2012 | 3 stars | Above average company |
| 2013 | 2 stars | Below average company |
| 2014 | 3 stars | Above average company |
| 2015 | 3 stars | Above average company |
| 2016 | 2 stars | Company requires improvement |
| 2017 | 3 stars | Good company |
| 2018 | 3 stars | Good company |
| 2019 | 3 stars | Good company |
| 2020 | 3 stars | Good company |
2. Total pollution incidents (sewerage) metric (category 1 to 3)
Main facts
For 2020:
- 292 actual incidents
- 29% fewer incidents per 10,000km sewer than in 2011
- 109,501km sewer length
Annual number of pollution incidents (category 1 to 3) from Thames Water sewerage assets, with EPA rating
2011 to 2015 data
| Year | 2011 | 2012 | 2013 | 2014 | 2015 |
|---|---|---|---|---|---|
| EPA status | green | amber | amber | amber | green |
| Incidents per 10,000km sewer | 38 | 68 | 90 | 76 | 38 |
| Actual incident numbers | 258 | 468 | 612 | 517 | 263 |
2016 to 2020 data
| Year | 2016 | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|---|
| EPA status | amber | amber | amber | amber | amber |
| Incidents per 10,000km sewer | 33 | 28 | 27 | 30 | 27 |
| Actual incident numbers | 357 | 303 | 297 | 325 | 292 |
Annual number of pollution incidents (category 1 to 3) from Thames 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 Thames Water was equivalent to 345 or fewer actual incidents in 2011 to 2015 and 279 or fewer in 2016 to 2020
- red status for Thames Water was equivalent to 885 or more actual incidents in 2011 to 2015, 542 or more in 2016 and 543 or more in 2017 to 2020
Number of pollution incidents (category 1 to 3) from Thames Water sewerage and clean water supply assets in 2020
| Asset type | Number of pollution incidents (category 1 to 3) |
|---|---|
| Combined sewer overflow | 0 |
| Foul sewer | 183 |
| Other water industry premises | 3 |
| Pumping station | 16 |
| Rising main | 18 |
| Sewage treatment works | 59 |
| Storm tank | 3 |
| Surface water outfall | 10 |
| Water distribution system (clean)* | 39 |
| Water treatment works (clean)* | 0 |
* 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:
- 27 sewerage pollution incidents per 10,000km of sewer - this is rated as amber
- performance was better than the sector average (33) for sewerage pollution incidents per 10,000km of sewer
- needed 279 or fewer actual sewerage pollution incidents to be rated as green
3. Serious pollution incidents (sewerage) metric (category 1 and 2)
Main facts
For 2020:
- 13 actual serious incidents
- 59% fewer serious incidents per 10,000km sewer than in 2011
Annual number of serious pollution incidents (category 1 and 2) from Thames Water sewerage assets, with EPA rating
2011 to 2015 data
| Year | 2011 | 2012 | 2013 | 2014 | 2015 |
|---|---|---|---|---|---|
| EPA status | amber | amber | amber | amber | amber |
| Serious incidents per 10,000km sewer | 2.9 | 2.2 | 3.2 | 2.3 | 1.8 |
| Actual serious incident numbers | 20 | 15 | 22 | 16 | 12 |
2016 to 2020 data
| Year | 2016 | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|---|
| EPA status | amber | amber | amber | amber | amber |
| Serious incidents per 10,000km sewer | 0.9 | 0.9 | 0.8 | 1.4 | 1.2 |
| Actual serious incident numbers | 10 | 10 | 9 | 15 | 13 |
Annual number of serious pollution incidents (category 1 and 2) from Thames 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 serious incidents required to fall within a particular RAG status:
- green status for Thames Water was equivalent to 10 or fewer actual serious incidents in 2011 to 2015 and 6 or fewer in 2016 to 2019
- red status for Thames Water was equivalent to 27 or more actual serious incidents in 2011 to 2015 and 16 or more in 2016 to 2019
Number of serious pollution incidents (category 1 and 2) from Thames 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 | 5 |
| Other water industry premises | 0 |
| Pumping station | 0 |
| Rising main | 1 |
| Sewage treatment works | 7 |
| 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:
- 1.2 serious sewerage pollution incidents per 10,000km of sewer - this is rated as amber
- performance was worse than the sector average (0.7) for serious sewerage pollution incidents per 10,000km of sewer
- needed 6 or fewer actual serious sewerage pollution incidents to be rated as green
4. Discharge permit compliance metric (numeric)
Main facts
For 2020:
- 349 permitted sewage treatment works (STW)
- 36 permitted water treatment works (WTW)
Annual discharge permit compliance (numeric) for Thames Water (STW and from 2016 includes WTW), with EPA rating
2011 to 2015 data
| Year | 2011 | 2012 | 2013 | 2014 | 2015 |
|---|---|---|---|---|---|
| EPA status | green | green | red | amber | green |
| Percentage permit compliance | 99.7 | 99.1 | 95.7 | 98.9 | 99.1 |
| Number of permitted STW | 345 | 345 | 350 | 348 | 346 |
| Number of non-compliant STW | 1 | 3 | 15 | 4 | 3 |
2016 to 2020 data
| Year | 2016 | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|---|
| EPA status | amber | green | green | green | green |
| Percentage permit compliance | 97.9 | 99.5 | 99.0 | 99.7 | 99.7 |
| Number of permitted STW | 349 | 348 | 349 | 349 | 349 |
| Number of permitted WTW | 34 | 35 | 35 | 36 | 36 |
| Number of non-compliant STW | 6 | 2 | 4 | 1 | 1 |
| Number of non-compliant WTW | 2 | 0 | 0 | 0 | 0 |
Annual discharge permit compliance (numeric) for Thames 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:
- 99.7% numeric discharge permit compliance - this is rated as green
- 99.7% numeric discharge permit compliance at STW and 100% discharge permit compliance at WTW
- performance was better than the sector average (99.2%) for numeric discharge permit compliance
- joint best performing company for numeric discharge permit compliance
5. Self-reporting of pollution incidents metric
Main facts
For 2020:
- 63% incidents self-reported
- 209 incidents self-reported
- 122 incidents reported by others
Annual self-reporting of pollution incidents (category 1 to 3) from Thames Water sewerage and clean water supply assets, with EPA rating
2011 to 2015 data
| Year | 2011 | 2012 | 2013 | 2014 | 2015 |
|---|---|---|---|---|---|
| EPA status | amber | amber | amber | amber | amber |
| Percentage of incidents self-reported | 46 | 50 | 58 | 53 | 61 |
| Number of incidents self-reported | 123 | 240 | 359 | 280 | 164 |
2016 to 2020 data
| Year | 2016 | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|---|
| EPA status | amber | amber | green | green | amber |
| Percentage of incidents self-reported | 67 | 73 | 76 | 78 | 63 |
| Number of incidents self-reported | 244 | 235 | 254 | 290 | 209 |
Annual self-reporting of pollution incidents (category 1 to 3) from Thames 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 Thames 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 | 0 | 0 |
| Foul sewer | 104 | 79 |
| Other water industry premises | 1 | 2 |
| Pumping station | 13 | 3 |
| Rising main | 14 | 4 |
| Sewage treatment works | 47 | 12 |
| Storm tank | 1 | 2 |
| Surface water outfall | 1 | 9 |
| Water distribution system (clean) | 28 | 11 |
| Water treatment works (clean) | 0 | 0 |
Self-reporting of serious pollution incidents (category 1 and 2) from Thames 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 | 5 |
| Other water industry premises | 0 | 0 |
| Pumping station | 0 | 0 |
| Rising main | 0 | 1 |
| Sewage treatment works | 5 | 2 |
| 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:
- 63% self-reporting of pollution incidents - this is rated as amber
- performance was worse than the sector average (77%) for self-reporting of pollution incidents
- worst performing company for self-reporting of pollution incidents
6. National Environment Programme (NEP) delivery metric
Main facts
For the financial year ending 2021:
- 48 Water Industry NEP (WINEP) schemes were completed to the planned deadline
- 1 scheme was not completed to the planned deadline
Annual delivery of the NEP (WINEP from April 2020) by Thames 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 | amber | green | green | green |
| Percentage of NEP complete to date (cumulative) | 109 | 96.8 | 102 | 102 | 100 |
| Cumulative number of schemes completed during AMP period | 49 | 60 | 87 | 130 | 10 |
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 | green | amber |
| Percentage of NEP complete to date (cumulative) | 100 | 100 | 100 | 99.3 | 98.0 |
| Cumulative number of schemes completed during AMP period | 64 | 133 | 172 | 265 | 48 |
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:
- 98.0% WINEP delivery - this is rated as amber
7. Sludge disposal and use metric
Main facts
For 2020:
- 210,981t (tonnes) total volume produced (dry matter)
- 35,864ha (hectares) land used for spreading
- 89% of sludge produced was used in agriculture
Annual compliance with sludge disposal and use metric by Thames 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 Thames 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 | 154.5 | 7.9 | 97.0 | 259.4 |
| 2012 | 128.5 | 11.9 | 96.0 | 236.4 |
| 2013 | 144.3 | 10.3 | 79.0 | 233.6 |
| 2014 | 170.7 | 14.2 | 72.6 | 257.4 |
| 2015 | 168.3 | 14.2 | 74.2 | 256.7 |
| 2016 | 177.8 | 8.6 | 73.5 | 260.0 |
| 2017 | 165.9 | 2.3 | 62.6 | 230.9 |
| 2018 | 173.2 | 3.5 | 45.7 | 222.4 |
| 2019 | 160.4 | 2.8 | 39.9 | 203.1 |
| 2020 | 187.3 | 0.5 | 23.2 | 211.0 |
8. Security of Supply Index (SoSI) metric
Main facts
For the financial year ending 2021:
- 6 water resource zones
- 2,596 Ml/d water distributed to the network (megalitres)
Annual compliance with SoSI by Thames Water, with EPA ratings
| Financial year ending | 2017 | 2018 | 2019 | 2020 | 2021 |
|---|---|---|---|---|---|
| EPA status | red | amber | amber | green | green |
| SoSI score | 99 | 97 | 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.
Thames Water storm overflows
| Year | 2020 |
|---|---|
| Total number of storm overflows | 472 |
| Number of storm overflows with annual data reported | 463 |
| Percentage of storm overflows with annual data reported | 98 |
| Average number of spills per storm overflow | 40 |
| Average duration of spill (hours) | 12 |