Annex A – Case studies
The Inspectorate publishes a variety of case studies on private water supplies on its website. These cover a range of scenarios and subjects, which are largely derived from enquiries to the Inspectorate, either from local authorities or private water supply users. Some come from third parties, including lawyers, agencies, local councillors, and MPs. These case studies show and share the range and diversity of issues and circumstances that can come about in relation to private water supplies. The additional benefit of their publication on the Inspectorate’s website is to make available the learning that can be taken from them.
There were five case studies compiled in 2024. These can be found on the website at Drinking Water Inspectorate (dwi.gov.uk).
A public supply that switched to being a private supply
This case study describes the difficulties that arose during a period of insufficiency on a private supply that until 2017 was a public supply. The change from public supply to private supply was driven by ‘the demands of the regulatory framework’ (Ofwat, 2017) on the small supply with around 2,000 consumers. It was acknowledged at the time that consumers would lose their statutory protections under the Water Industry Act 1991, which includes alternative supplies should the mains supply fail. Currently, across England and Wales there are several small operations providing drinking water supplies as licenced suppliers. These include Albion Water with 3,000 consumers and ESP Water with 3855 consumers. In moving from being a public supply to a private one, it created several new challenges for those responsible for its maintenance and upkeep under private supply legislation. These challenges caused considerable impact to consumers during this period of insufficiency. These issues are not uncommon to shared private supplies and are exemplified in this case study. This case study also shows that whilst the switch from a public supply to a private supply resolved some of the problems that led to it, it created others which resulted in risk to consumers. These were not necessarily anticipated and/or proactively managed to prevent or mitigate these risks for a variety of reasons, when the switch was made. Often this is due to financial or resource limitations, or where the local authority has not used its powers to facilitate mitigation to prevent or adequately manage the risk.
Hospital case revisited
In the Inspectorate’s report for the year 2013, it described the reasons why a newly installed private water supply serving a large regional hospital was never fully commissioned into use, despite the considerable costs it incurred. This case had some bearing on the revision of the Regulations in 2016. The Inspectorate revisited this case in 2024. It learned that the then new borehole at the hospital was never used as intended. Therefore, the considerable time, effort and costs were unfortunately and ultimately lost to this well intended project. This case study challenges the effectiveness of current private water supply regulation in protecting consumers in a way that is equitable to public drinking water supplies.
Purchasing a property served by a private supply
This case study exemplifies why prospective buyers of property served by a private water supply should consider any implications or potential risks associated with the supply prior to any purchase. Supply arrangements vary from one to another and the responsibilities in their management and maintenance are not always clear or documented. This can cause later difficulties and disagreement between the parties involved when situations change. Unfortunately, this is because any potential impacts these discrepancies may cause are often overlooked because robust checks are not made during the property conveyancing process. This case study shows one such example.
Deficiencies in proactive risk assessment on a regulation 9 supply
This case study concerns a regulation 9 supply providing water for domestic purposes to over 300 consumers. Sampling by the local authority highlighted a rising trend in arsenic concentrations, which presented a potential danger to human health. The local authority did not however investigate the root cause of the arsenic in accordance with regulation 16 or serve a regulation 18 notice to secure a permanent, long-term solution as the Regulations required them to do under these circumstances. Instead, when test results were over the maximum concentration stipulated in the Regulations, the site would be temporarily switched over to a back-up mains water supply until maintenance on inadequate treatment was completed. This reactive approach is contrary to the proactive risk-based approach that the Regulations require as it does not fully mitigate the risk or address the root cause in the long term to protect consumers.
Registration of private water supplies
It is not a legal requirement for consumers, owners or indeed anyone, to register private water supplies with the local authority. Many choose not to, whilst others are just not aware of the Regulations and/or that the Regulations place duties on local authorities to test and risk assess them (excluding that serve single dwellings exclusively). If a local authority is not made aware of a supply in its area, it cannot carry out its duties as required to protect the consumers of that supply. This presents a potential risk that can have unforeseen consequences as this case study illustrates.