A public supply that switched to being a private water supply
Background
It is not unusual for owners and users of private water supplies to seek a connection to the public supply system to provide an alternative, or a back-up arrangement to a private water supply. This is often the case where private supplies are failing, unreliable or where it overcomes difficulties in managing and maintaining a supply, whatever the reason. This however is only an option when connection fees are not cost prohibitive and or the parties concerned agree with such a forward plan.
Much less common is where a water undertaker relinquishes its licence as a water supplier of a public supply system but continues to provide water intended for human consumption to consumers as a private supply. The circumstances and reasons for so doing are likely to be case specific and probably financial, and in theory such a switch should not result in overall detriment to public health or consumer confidence. This is partly because the regulations for both public and private water supplies were originally transposed from the same European Directive. This means that the standards of wholesomeness are the same in both sets of regulations, and among other similarities they are both also risk based. Despite this, consumers on private supplies are nevertheless generally at greater risk than those on public supplies for a variety of reasons.
Public to private supply
Since the inception of the regulations in 2010, there has been only one case where a public water supply provided by a licenced undertaker, has changed to become a private supply. This transfer took place in 2017 and concerns a supply in north-west Hampshire on the Wiltshire border, which serves over 700 residential properties and 50 or so commercial premises (approximately 2000 people). When circumstances change in this way, the regulation of the water quality on the supply remains in place, albeit under different (private water supplies) regulations. This is to ensure that consumers are afforded the same level of protection, irrespective of the regulatory body. However, an independent scientific project commissioned by the Inspectorate in 2023, (see link to project reports) concluded that, whilst this was undoubtedly the intension of the regulations, the regulation of private supplies is not equitable with public supplies. Consequently, consumers that were served by a once public supply may be subject to an increased risk on being transferred to a private supply.
Episode of insufficiency on the supply
In 2024 Defra and the Inspectorate were made aware that consumers on the above-mentioned supply had experienced a loss of water supply in May 2024.
This occurred when the abstraction pump at the source failed early in the morning of Sunday 5 May 2024. This meant that the main service reservoir could not be replenished, and consumers suffered a loss of water supply from around 09:00 on Monday 6 May. Although the supply had a secondary back-up, this failed. Another temporary pump was sourced to keep the supply going, but it was unreliable. This occurred on a bank holiday and attempts to contact the specialist water engineering companies to carry out repairs also failed as they were unavailable.
As a result of this, further reactive calls were made and fortunately an electrical engineer from a company that was regularly used was available and visited the site on the following Sunday, almost a week later. He confirmed that the windings on the pump had failed, and a replacement pump was needed.
Temporary bottled water supplies were sought in the meantime. This was hampered initially because the local water company no longer held back-up bottled water stocks contrary to the supply owner’s knowledge. To counter this, an order was made straightaway with Water Direct; however, it was not until the next day that the first of several deliveries was made. Stocks were limited due to an unusually high demand from two major water companies in the south that were experiencing a loss of supply themselves and were using all available supplies including tankers, static tanks and bowsers. In the meantime, five tanker deliveries of 18,000 m3 each were made to keep consumers supplied with water. Despite this, the tankers were not able to keep pace with the demand from affected consumers.
When bottled water did arrive, the supply operating company found it difficult to resource deliveries to the affected households, although they ensured that vulnerable consumers were the first to receive these temporary supplies.
From Tuesday 7 May onwards 32 tankers discharged into the main service reservoir. Further tankers ran a shuttle service between the borehole hydrant and the reservoir, delivering a total of 640 cubic metresto keep consumers supplied.
A site survey for the installation of a new abstraction pump was completed on Tuesday 7 May and a new replacement 23 kW pump was ordered. In the meantime, the operating company were loaned a 9 cubic metre/hour borehole test pump, which was installed and used to supply the high-level secondary service reservoir for daytime use, with the main service reservoir being used at night. The new pump was delivered, tested and installed on the following Friday. After flushing the system through hydrants both at the works and the villages, water supplies to the main reservoir commenced at 16:30. The supply was fully restored by 17:30 that day.
Root causes and learning
It is not unusual for pumps to fail or a supply to become insufficient for some other reason. These risks can however be controlled to some extent through robust management, planning and contingencies. These are risks that must be assessed by the local authority in a proactive manner through the regulation 6 risk assessment process. To mitigate these situations, it is essential that adequate and reliable contingency procedures and arrangements are in place for any repairs or other outages, including those arising out of hours or during holiday periods. Most importantly this must include reliable arrangements for the timely sourcing of temporary supplies whilst the supply is out of action. In this case the supply owners found this challenging but did all they could to keep consumers supplied under difficult circumstances. This was demanding and often reactive and reliant on good fortune, due to need and unforeseen or unplanned circumstances. Some of this was unpredictable but nevertheless learning was taken from this event and to date procedures have been reviewed and updated to prevent recurrence of a similar nature. For example, it was recognised following this event that a more robust process of bottled water delivery was required and that the list of consumers who require special assistance needed updating.
Root causes of insufficiency occur for various reasons, for example due to a lack of maintenance or upkeep of a system. This itself may be due to resource or funding difficulties. In other situations, there is a fundamental lack of ownership of supply management. Sometimes too where there is ownership it is disputed amongst stakeholders, or it is not legally binding causing added complications. These situations all present risk to the wholesomeness and sufficiency of the supply and must be considered by the local authority as part of the risk assessment process by scoring the likelihood of hazards and hazardous events versus their severity.
Where robust contingencies are not in place, periods of insufficiency are largely managed by best endeavours in a reactive manner by need. This is contrary to modern risk-based regulation and as this case study shows in part, this can result in challenges to the supply owner (where one exists), including sourcing alternative supplies reactively in the heat of the moment of through established and agreed arrangements. This approach is high risk and is likely to leave supplies without adequate resilience and is unsustainable in the long term. As a result, the extent to which consumers can be assured of a wholesome and sufficient supply is much less than it would be for customers of water undertakers and licenced suppliers providing a public supply. Where arrangements are in place, they must be reviewed and updated on a suitably regular basis.
Where necessary local authorities must use their enforcement powers to ensure that those responsible for the management and maintenance of private water supplies proactively put in place robust arrangements for emergency scenarios.
Updated 14 May 2025