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 incident
Company and issue
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.
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.
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).
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&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 450mm burst main (2013/3889).