Thames Water Utilities Limited – AMP8 PFAS Strategy

Water Industry Act 1991 (as amended) (“the Act”): Section 19(1)(b)

Reference: TMS-2023-00012

Version: 2

Acceptance Notice:

The Drinking Water Inspectorate, on behalf of the Secretary of State for Environment, Food, and Rural Affairs:

1. Is satisfied that Thames Water Utilities Limited “the Company” in supplying water from all water supply systems (raw water assets, water treatment works and treated water assets), which are for the time being listed in the Annex to this Schedule of Works which may be at risk of breaching the wholesomeness and no deterioration standards due to PFAS concentrations. This means that the Company is likely to contravene its duties under Sections 68(1)(a) and 68(1)(b) of the Act and the requirement set in regulation 4(2)(b) of the Water Supply (Water Quality) Regulations 2016 (as amended) (“the Regulations”).
2. Has notified the Company on 22 November 2023 that the Secretary of State considering making in relation to the company an enforcement order under Section 18 of the Act.
3. Notes that the Company has on 24 June 2024 given a new undertaking under Section 19 (1) (b) of the Act, to take the following steps by the dates shown.

Steps to be taken:

1. Ensure that PFAS have been assessed as a hazard, as part of the regulation 27 Risk Assessment for the supply systems listed in the Annex to this Schedule, according to a Drinking Water Safety Plan approach and the Inspectorate’s latest guidance on the risk assessment of individual and total PFAS. Ensure that regulation 28 documents are reviewed (at least annually) and updates provided as necessary.
   Date: Ongoing for the duration of the undertaking.
2. Keep under review the company’s strategy for the protection of public health and for compliance with drinking water quality standards with respect to PFAS.
   Date: Ongoing for the duration of the undertaking.
3. Conduct surveillance, including sampling and analysis for PFAS in line with the Inspectorate’s latest published guidance on PFAS.
   Date: Ongoing for the duration of the undertaking.
4. Produce a prioritised list of sites for additional investigation in step 5. below
   Date: 31 March 2025
5. Where there are new PFAS detections, or a change in the detected levels, conduct operational monitoring; sampling (and analysis) extended upstream of abstraction points into catchments and sub-catchments, and downstream through different stages of water treatment to the final water sampling location, to identify the source, concentration and fate of PFAS compounds.
   Date: Ongoing for the duration of the undertaking.
6. Following on from step 4, continue to conduct risk-based, enhanced, investigatory sampling (and analysis), where PFAS are detected.
   Date: Ongoing for the duration of the undertaking.
7. Undertake catchment characterisation and identification of PFAS sources (minimum requirements defined in DWI guidance), for example, product usage (existing data available and data gathering), catchment modelling with analysis of weather, surface and groundwater flows, catchment walkovers, identification of high-risk locations.
   Date: Ongoing for the duration of the undertaking.
8. Initiate and maintain regular engagement with relevant stakeholders, to ensure that catchment risk assessments are current.
   Date: Ongoing for the duration of the undertaking.
9. Participate in relevant research and development activities.
   Date: Ongoing for the duration of the undertaking.
10. Where PFAS are detected in a single final water (or downstream treated water) sample, or two or more raw water (water sampled from any point prior to the final treated water point at the water treatment works) samples in a supply system not currently listed in the annex to this undertaking, submit a change request to the Inspectorate to add the supply system to the annex, unless a mitigation plan has already been developed for this supply system.
    Date: Ongoing for the duration of the undertaking.
11. Maintain and continually review the company’s PFAS strategy.
    Date: Ongoing for the duration of the undertaking.
12. For all sources that fall into tier 3, design, develop and implement mitigation to reduce PFAS concentrations in drinking water to at least tier 1 concentrations, with a high priority.
    Date: Ongoing for the duration of the undertaking.
13. For all sources that fall into tier 2, design a proactive and systematic risk reduction strategy which shall include a prioritised mitigation methodology to progressively reduce PFAS concentrations in drinking water.
    Date: Ongoing for the duration of the undertaking.
14. For all sources that fall into tier 1, design a basic mitigation plan, which can be implemented should concentrations increase, or toxicological or other information change that requires mitigation be delivered.
    Date: 31 March 2030

Reporting:

1. At regular intervals provide the Inspectorate with reports on progress made with carrying out the steps set out in the Action Plan. Reports to include at least the following details:
   a) All sampling and analysis data from the monitoring of raw and treated water in the supply systems named in the annex.
   b) Details of the remedial steps that comprise the programme of work including commencement and completion dates for investigations, design, tendering, construction, and commissioning.
   c) Current state of progress with the steps referred to in 1b) above.
   d) A summary of progress with the ongoing measures in the steps to be taken section.
   e) A statement of implications of any slippage of the programme and details of activities planned to bring programme back on target.
   f) Whether the company has any other reason to believe it may not be able to meet any of the key dates set out in this Schedule of Work.
   g) The latest version of the company’s PFAS strategy.
   h) Evidence of no PFAS detections above Tier 1 in a supply system for one year and evidence of the mitigation plan, in order to remove the supply system from the undertaking annex .
   Date: Annually for the duration of the Undertaking. Reporting periods are Jan – Dec. Reports to be submitted by 31 January each year that the Undertaking is in place.
2. Submit prioritised list of sites for additional investigation in step 4.
   Date: 30 April 2025
3. Continue to test at an enhanced frequency for PFAS for a period of 12 months following commissioning of any work associated with the Action Plan to demonstrate the effectiveness of the remedial measures taken.
   Date: 31 March 2031
4. Provide a final report to the Inspectorate on the efficacy of the steps taken as part of this undertaking. Include, as evidence of closure for this scheme, appropriate documentation to confirm that the actions set out in this Schedule of Work have been completed satisfactorily and that the company’s PFAS strategy is in place.
   Date: 30 April 2031

Further Details of this Acceptance Notice:

4. The Secretary of State satisfied that Thames Water Utilities Limited has given and is complying with an undertaking to take all such steps as appear to the Secretary of State for the time being to be appropriate to secure or facilitate compliance with the requirement of regulation 4(2)(b) of the Water Supply (Water Quality) Regulations 2016 (as amended).

Authorised by the Secretary of State to sign in that behalf

Nicholas Adjei
Deputy Chief Inspector, Drinking Water Inspectorate
1 November 2024
Reference: TMS-2023-00012 v2

Annex A to Schedule for TMS-2023-00012 – Thames Water Utilities Limited

Undertaking in respect of PFAS

Supply System Name	Population	Risk Assessment Reference (name of Regulation 28 Report or Supply System Reference)
East Croydon	40,670	TMS1167 – Addington
Westerham	10,352	TMS1231 – Westerham
Beckenham	41,711	TMS1173 – Bickley
Bromley Town	67,738	TMS1173 – Bickley
Bermondsey	83,304	TMS1197 – Hampton 30/36
Eltham Park	55,444	TMS1174 – Castlewood
Petts Wood	64,446	TMS1192 – Farnborough
Orpington	40,920	TMS1192 – Farnborough
North Downs	28,145	TMS1206 – Knockholt
New Cross	49,206	TMS1210 – New Cross & Riverside
Thamesmead	71,762	TMS1210 – New Cross & Riverside
Central Sydenham	41,824	TMS1213 – Norwood
East Sydenham	51,548	TMS1173 – Bickley
Kidbrooke	44,394	TMS1215 – Oxleas Wood
Bexleyheath	50,122	TMS1215 – Oxleas Wood
Charlton	60,105	TMS1210 – New Cross & Riverside
Abbey Wood	84,850	TMS1210 – New Cross & Riverside
Croydon Woodside	46,383	TMS1213 – Norwood
Rotherhithe	47,428	TMS1197 – Hampton 30/36
Bellingham & Mottingham	60,004	TMS1173 – Bickley
Lewisham South	57,698	TMS1215 – Oxleas Wood
Lewisham North	41,371	TMS1215 – Oxleas Wood
Plumstead	63,239	TMS1215 – Oxleas Wood
Shooters Hill	6,830	TMS1174 – Castlewood
South Lambeth	75,731	TMS1197 – Hampton 30/36
East Lambeth	65,392	TMS1197 – Hampton 30/36
Crystal Palace & Norwood Park	39,665	TMS1187 – Crystal Palace
Norwood & Forest Hill	51,009	TMS1187 – Crystal Palace
Barnes	50,699	TMS1197 – Hampton 30/36
Battersea North	39,632	TMS1197 – Hampton 30/36
Battersea South	68,048	TMS1197 – Hampton 30/36
Mitcham	35,094	TMS1198 – Hampton 42
Dulwich	35,186	TMS1214 – Nunhead
North Streatham	72,153	TMS1213 – Norwood
Peckham	62,260	TMS1214 – Nunhead
Putney Heath	52,909	TMS1213 – Norwood
North Croydon	36,086	TMS1213 – Norwood
Balham	36,997	TMS1198 – Hampton 42
Brixton	47,011	TMS1198 – Hampton 42
Kingston North	44,978	TMS1224 – Surbiton 30″
Kingston South	32,594	TMS1224 – Surbiton 30″
Merton	74,350	TMS1224 – Surbiton 30″
Tooting	55,892	TMS1224 – Surbiton 30″
North Lambeth	54,900	TMS1197 – Hampton 30/36
Berrylands & Long Ditton	57,243	TMS1177 – Chessington
South Streatham & West Dulwich	75,302	TMS1198 – Hampton 42
Wandsworth East	55,965	TMS1213 – Norwood
New Malden	20,934	TMS1224 – Surbiton 30″
Streatham East	20,889	TMS1213 – Norwood
West Enfield	52,842	TMS1183 – Cockfosters
Oakwood	26,134	TMS1183 – Cockfosters
Picketts Lock	19,263	TMS1219 – Sewardstone
South Tottenham	38,355	TMS1186 – Crouch Hill
Bowes Park	28,796	TMS1186 – Crouch Hill
South Enfield	69,062	TMS1186 – Crouch Hill
Haringey West	58,103	TMS1219 – Sewardstone
Bush Hill	51,396	TMS1219 – Sewardstone
Southgate	40,133	TMS1219 – Sewardstone
Cheshunt	55,103	TMS1219 – Sewardstone
Waltham Abbey	36,680	TMS1219 – Sewardstone
Enfield Town	39,096	TMS1219 – Sewardstone
City	82,246	TMS1186 – Crouch Hill
Whitechapel	33,561	TMS1194 – Finsbury Park
Pentonville	55,092	TMS1207 – Maiden Lane
Bloomsbury	58,771	TMS1207 – Maiden Lane
Hackney West	45,982	TMS1186 – Crouch Hill
Stamford Hill	76,284	TMS1186 – Crouch Hill
Shacklewell and Canonbury	29,586	TMS1186 – Crouch Hill
Hackney South	69,895	TMS1186 – Crouch Hill
Holloway	81,016	TMS1207 – Maiden Lane
Kentish Town	44,540	TMS1207 – Maiden Lane
Willesden	76,064	TMS1220 – Shootup Hill
South Hampstead	29,993	TMS1209 – Mill Hill
Brent Cross	72,536	TMS1209 – Mill Hill
Gunnersbury	45,398	TMS1189 – Ealing
South Ealing	76,549	TMS1189 – Ealing
North Ealing	61,918	TMS1189 – Ealing
Fulham	60,605	TMS1216 – Putney
Hurlingham	37,628	TMS1216 – Putney
Parliament	64,968	TMS1216 – Putney
South Kensington	42,663	TMS1216 – Putney
Chiswick & Hammersmith	70,708	TMS1172 – Barrow Hill
Knightsbridge	65,600	TMS1220 – Shootup Hill
Brent South	82,496	TMS1172 – Barrow Hill
St Johns Wood & Mayfair	70,916	TMS1220 – Shootup Hill
Kensington	78,395	TMS1172 – Barrow Hill
Brondesbury	13,111	TMS1209 – Mill Hill
Muswell Hill & Hampstead Heath	75,133	TMS1196 – Hampstead
Sunbury West	14,521	TMS1199 – Hampton Country
Kings Cross	39,157	TMS1172 – Barrow Hill
Chelsea	62,596	TMS1216 – Putney
Marylebone & Paddington	69,073	TMS1172 – Barrow Hill
Holborn	12,290	TMS1172 – Barrow Hill
Crouch End & Gospel Oak	73,850	TMS1203 – Hornsey Lane
Radnage	7,685	TMS1235 – Wycombe
Marlow	19,295	TMS1235 – Wycombe
Aylesbury North	63,243	TMS1170 – Aylesbury
Aylesbury South	55,381	TMS1170 – Aylesbury
Aylesbury East Cholesbury	4,195	TMS1229 – Tring
Dagnall	1,138	TMS1229 – Tring
Tring	19,620	TMS1229 – Tring
Aylesbury Southwest	24,584	TMS1170 – Aylesbury
Little Hampden	2,528	TMS1170 – Aylesbury
Wycombe South North & Central	75,419	TMS1235 – Wycombe
Flackwell Heath	11,248	TMS1221 – Slough
Chinnor Watlington & Chalgrove	16,219	TMS1179 – Chinnor
Quainton Reservoir	100	YTMS2001 – Aylesbury
Hoddesdon	41,241	TMS1202 – Hoddesdon
Goffs Oak	26,796	TMS1202 – Hoddesdon
Upshire	2,147	TMS1219 – Sewardstone
Epping Forest	37,986	TMS1201 – High Beech
Roding Valley	52,023	TMS1178 – Chigwell
Edmonton	58,944	TMS1234 – Woodford
North Tottenham	80,306	TMS1234 – Woodford
Hainault	61,158	TMS1178 – Chigwell
Highams Park	42,659	TMS1178 – Chigwell
Woodford	49,582	TMS1178 – Chigwell
Clapton	79,725	TMS1194 – Finsbury Park
Bethnal Green	65,198	TMS1194 – Finsbury Park
Globe Town	48,020	TMS1194 – Finsbury Park
Bow	41,298	TMS1194 – Finsbury Park
Isle of Dogs North	82,861	TMS1194 – Finsbury Park
Isle of Dogs South	63,647	TMS1194 – Finsbury Park
Highbury	59,710	TMS1207 – Maiden Lane
Walthamstow	85,540	TMS1234 – Woodford
Leytonstone	45,053	TMS1234 – Woodford
Wanstead Park	38,075	TMS1234 – Woodford
West Ham	38,997	TMS1234 – Woodford
Plashet Park	45,237	TMS1234 – Woodford
Wall End	45,770	TMS1234 – Woodford
Stepney	62,097	TMS1194 – Finsbury Park
Manor Park	46,010	TMS1234 – Woodford
Upton	56,364	TMS1234 – Woodford
Stratford East	55,993	TMS1234 – Woodford
Stratford West	62,411	TMS1234 – Woodford
Royal Docks East	39,875	TMS1234 – Woodford
Royal Docks West	60,141	TMS1234 – Woodford
Farnham Common	10,342	TMS1221 – Slough
Windsor & Colnbrook	50,712	TMS1221 – Slough
Slough East	66,083	TMS1221 – Slough
Slough South	53,257	TMS1221 – Slough
Slough North	61,947	TMS1221 – Slough
Didcot	47,353	TMS1182 – Cleeve
Abingdon	17,946	TMS1166 – Abingdon
Banbury	65,381	TMS1171 – Banbury
Bicester	47,133	TMS1188 – Deddington & Bicester
Charlbury Overnorton & Woodstock	25,882	TMS1233 – Witney
Deddington	17,303	TMS1188 – Deddington & Bicester
East Oxford	41,745	TMS1227 – Thame
Boars Hill	19,406	TMS1175 – Central Oxford (inc Kidlington & Boars Hill)
Central Oxford	67,810	TMS1175 – Central Oxford (inc Kidlington & Boars Hill)
Thame	28,269	TMS1227 – Thame
Cowley Littlemore & Nuneham	72,182	TMS1227 – Thame
West Oxford & Kidlington	37,930	TMS1175 – Central Oxford (inc Kidlington & Boars Hill)
Hook Norton	9,632	TMS1188 – Deddington & Bicester
Marcham	6,785	TMS1166 – Abingdon
Northcourt	19,912	TMS1166 – Abingdon
Faringdon Town	15,137	TMS1168 – Ashbury
Shrivenham & Ashbury	9,184	TMS1168 – Ashbury
West Wickham	23,676	TMS1192 – Farnborough
Richmond	59,506	TMS1197 – Hampton 30/36
Wandsworth Wandle	48,169	TMS1197 – Hampton 30/36
Clapham	41,900	TMS1197 – Hampton 30/36
Wimbledon	32,008	TMS1198 – Hampton 42
Norbury	39,460	TMS1213 – Norwood
Molesey	37,980	TMS1224 – Surbiton 30″
Whitton	52,741	TMS1199 – Hampton Country
Syon Park	46,278	TMS1199 – Hampton Country
Shepherds Bush	45,872	TMS1199 – Hampton Country
Sunbury East	33,288	TMS1199 – Hampton Country
Teddington	67,400	TMS1199 – Hampton Country
Hanger Lane & Stonebridge	27,762	TMS1205 – Kempton 48
Hounslow Heath	54,534	TMS1205 – Kempton 48
Kilburn	81,670	TMS1220 – Shootup Hill
Hendon & Neasden	56,931	TMS1209 – Mill Hill
Heston	43,996	TMS1205 – Kempton 48
West Hampstead	42,692	TMS1209 – Mill Hill
Brightwalton	1,262	TMS1184 – Compton
Compton	3,478	TMS1184 – Compton
Ilsley	2,213	TMS1184 – Compton
Keston & Forestdale	47,678	TMS1192 – Farnborough
Witney	54,780	TMS1233 – Witney
Carterton	22,858	TMS1233 – Witney
West Croydon Upper	40,313	TMS1218 – Russell Hill
West Croydon Lower	61,729	TMS1218 – Russell Hill
Lambourn	5,255	TMS1211 – Newbury
Woodlands	1,126	TMS1211 – Newbury
South Darenth	41,050	TMS1222 – Southfleet
Sidcup & Elmstead Wood	46,740	TMS1193 – Farningham Hill
Swanley	28,520	TMS1193 – Farningham Hill
Cray	21,636	TMS1193 – Farningham Hill
Burghfield & Tadley	30,276	TMS1217 – Reading
Beenham	4,349	TMS1217 – Reading