Warning Letters

These letters are served as a warning to the company that any further repeat events of this nature could result in further sanctions, including enforcement or prosecution.

Date of event	Date of letter	Event details
21 July to 6 September 2023	4 July 2024	United Utilities was issued with a warning letter following a planned source water change during July 2023. The company risk assessment did not adequately consider how the source water change would impact consumers and the company also failed to fully implement learning from a previous similar event. The company has since updated its risk assessment procedures and undertaken consumer acceptability research to prevent a recurrence.
10 November 2023	4 April 2024	Dwr Cymru Welsh Water was issued with a warning letter following an event involving the supply of water to consumers that had not been subjected to appropriate pH correction and disinfection processes. An improvement notice was served on the company on 21 May 2024.
7 November 2022	29 December 2023	Southern Water was issued a warning letter following the identification of inappropriately applied and unapproved products at the Rainham Mark service reservoir in Kent. Following the identification of the issues, the company promptly removed the service reservoir from supply and completed an extensive investigation into the issue. It has since improved its internal procedures, training and controls of the use of approved products.
22 March 2023	10 November 2023	Thames Water was issued with a warning letter after a burst main downstream of Chinnor works allowed water to be supplied from the works in contravention of a notice to prevent supplies pending remedial work. Thames Water identified an error in closing valves had caused the problem and had inadvertently breached the notice. The company took prompt actions to prevent recurrence by isolating the works and updating their internal procedures.
6 July 2023	20 October 2023	United Utilities was issued with a warning letter following the connection of a water main to a final effluent main at Rossendale Wastewater Treatment Works (WwTW). Discoloured water, which contained faecal bacteria was subsequently supplied to the WwTW. The event occurred after the mains were inadvertently cross connected, during capital maintenance works at the WwTW, and was solely confined to the WwTW itself. The company took action to mitigate the risk, by issuing prohibitive advice as well as disinfecting the water supply system at the WwTW and sampling.
21 June 2021	4 April 2023	Northumbrian Water was issued with a warning letter following the connection of two properties to an abandoned main that held groundwater runoff. Property one had been left connected to the abandoned main since 2006 as it was missed during the transfer of properties to a new mains network in the area. A second property was built in 2018 and this was connected onto the supply pipe of the first property, thus also connecting it to the abandoned main. The company has taken actions to prevent a recurrence, including reviewing its mains replacement procedure, replacing the supply pipes of both properties concerned and connecting both properties onto the correct mains network.
30 July 2021	9 January 2023	The Clancy Group considered a relevant person under section 70(1)b of the Water Industry Act 1991, were issued with a warning letter following an event whereby two properties in Deal, Kent were supplied with water which had a hydrocarbon taste and odour following the installation of a new communication pipe. The Clancy Group did not follow the relevant procedure which required certain water quality tests to be completed. Since the event, the company has given ‘toolbox talks’ to its employees and discussed the circumstances of the event with peers in the industry.
19 July 2021	30 November 2022	United Utilities was issued with a warning letter following the supply of water to consumers that had not been subjected to appropriate disinfection processes from the Watergrove water treatment works. The company subsequently implemented remedial measures to prevent a recurrence (Ref:2021/8164).
5 October 2021	26 August 2022	SES Water was issued with a warning letter following the supply of water containing faecal material. The event occurred following a planned internal inspection and clean of the treated water tank at Westwood works, resulting in the company issuing a precautionary boil water notice to affected consumers. The company has taken actions to prevent a recurrence, including a programme to improve resilience in supply.
27 December 2021	21 July 2022	Southern Water was issued with a warning letter following an event at Testwood works where issues of the operation of the auto-coagulation and UV systems led to treated water storage levels becoming low, resulting in discoloured and unwholesome water being supplied which was rejected by consumers. The company has an enforcement notice (SRN3911) in place which include steps to upgrade the treatment process at Testwood works.
17 December 2020	13 January 2022	Affinity Water received a warning letter following increased levels of turbidity entering the contact tank and being supplied from Batchworth works during a trial to increase flows. The company subsequently took action to prevent a recurrence.
6 November 2020	19 August 2021	Northumbrian Water was issued with a warning letter following an event involving the supply of water to consumers that had not been subjected to appropriate treatment. This resulted in the company issuing a boil water notice and providing alternative water supplies to affected consumers.
6 April 2021	26 July 2021	South Staffordshire Water was issued with a warning letter following an event involving the supply of water that had not been subjected to appropriate treatment and disinfection processes. The Inspectorate concluded that the company did not have adequate control measures in place to prevent the supply of untreated water from Little Hay works and failed to take timely action to investigate a telemetry fault. Once the company became aware of the failure it took steps to investigate and rectify the issues found.
2015	16 March 2021	Southern Water was issued with a warning letter after it emerged in 2015 that the company had been bypassing fail-safe mechanisms at treatment works in Kent. In some cases this was done deliberately, and the company admitted supplying inadequately disinfected water as a consequence.
4 May and 29 May 2020	16 September 2020	South Staffordshire Water received a warning letter following two odour failures within the Walsall South Zone. These were caused by Geosmin leaving Hampton Loade treatment works. A notice was already in place for taste and odour at this works (SST_2019_00001) which the company were found to be in breach of. Due to mitigating factors additional enforcement was not deemed appropriate (SST_2020_00004)
4 September 2018	25 November 2019	Dwr Cymru Welsh Water received a warning letter following investigations into consumer complaints about unusual tastes and odours in Pontardawe, near Swansea. This was caused by the company following planned work in the distribution network (2018-6797).
2 July 2018	3 June 2019	SES Water received a warning letter following investigations into levels of turbidity in excess of those stipulated within the regulations entering the contact tank at Woodmansterne water treatment works.  This was a near identical repeat of an event in 2012, the company have taken steps to make a repeat event unlikely to recur (2018-6666).
July and December 2017	29 August 2018	Severn Trent Water received two warning letters following investigations into two incidents at service reservoirs operated by the company. The first incident was associated with the detection of faecal contamination in Mapperley service reservoir, Nottingham in July 2017, following an over-filling event. The second incident was associated with the detection of faecal contamination in High Service Reservoir, Derby in December 2017 following a period of heavy rain when the roof membrane was defective. The Inspectorate subsequently identified evidence of livestock faeces on the roof of the reservoir. The Inspectorate concluded that the company was negligent in not preventing both these events and, in each case, failed to take adequate steps to protect public health. (2017/6164 and 2017/6388).
Various 2017	15 November 2017	Northumbrian Water received two warning letters after the Inspectorate identified use of unapproved produces in the treatment process at Murton works, during a technical audit which was undertaken in response to a series of events at Murton where water of low pH was supplied (2017/5978;6038;6084). The second warning letter was issued because the company provided incorrect information in its final report on one of these events.
26 September 2016	16 November 2017	United Utilities received a warning letter following investigation of an incident where contamination from a stockpile of paper pulp entered the Thirlmere (raw water) aqueduct.  Organic chemicals in the wood pulp caused an unacceptable taste and odour in water supplied to consumers from Lostock treatment works (2016/5764)
5 March 2016	13 October 2017	United Utilities received a warning letter following the detection of Cryptosporidium in water supplied from Woodgate Hill treatment works whilst roof repairs were being carried out on the final contact tank (2016/5456).
20 January 2016	22 September 2017	South East Water was issued with a warning letter  following investigation of an incident where consumers reported an unacceptable taste and odour in their tap water supply. The issue was caused by stagnant water from an abandoned asset at Groombridge treatment works entering the supply (2016/5407).
20 September 2016	7 April 2017	SES Water received a warning letter following the investigation of a mains misconnection to a private supply in Worcester Park (2016/5760) in which unwholesome water was supplied.
4 January 2016	12 December 2016	Wessex Water received a warning letter following investigation of the Chard incident (2016/5379) in which water unfit and unwholesome was supplied.
9 May 2014	12 December 2016	Severn Trent Water received a warning letter following the investigation of the Cleeve incident (2014/4451) in which water unfit and unwholesome was supplied.
24 and 25 December 2013	6 December 2016	Wessex Water received a warning letter following the investigation of the Ivyfield incident (2014/4374) where the company failed to adequately disinfect water leaving its Ivyfield works.
26 January 2013	12 July 2013	Cambridge Water was issued with a warning letter following the company’s failure to notify the Inspectorate of a reportable event  – Oakington 450 mm burst main (2013/3889).