Private Water Supplies - Case Study

A private water supply with restriction of use advice in place for three years

Water Quality Issues

Faecal contamination – a supply that constitutes a potential danger to human health.

Parties involved

A local authority, the Inspectorate, supply consumers, a supply managing agent, landowners, the local authority Ombudsman.

Supply type

Regulation 9 (due to tenancy arrangements)

Relevant Regulations 

Regulations 6, 7, 9, 12, 14, 16 and 18

Action to protect consumers 

Restriction of use, remedial work on the supply assets, the need for management and maintenance of the supply, and associated record keeping.

Water Quality issue resolved? 



The regulatory requirement to initiate timely enforcement.

Examples of the consequences of not initiating timely enforcement.

Impact on consumer confidence of failing supplies.


This case study concerns a private water supply that serves eight dwellings. The source of the supply is a spring that serves these properties via gravity-fed storage tanks. The supply is not treated as a whole, although some of the properties are fitted with UV disinfection units. The supply is maintained by a professional managing agent on behalf of the owner of the land serving the properties. The supply is subject to the requirements of regulation 9 of The Private Water Supplies (England) Regulations 2016 (as amended) “the Regulations”, which applies to all large supplies and those used as part of a commercial or public activity. In this case some of the dwellings that are fed by the supply are tenanted which is a “commercial use” of the supply.

Risk Assessment and sampling

The Regulations require that a local authority must complete a risk assessment for every private water supply in its area and review and update that risk assessment every five years. The monitoring requirements are determined by the volume of water consumed. These fundamental requirements have been in place since 2010 under prior and amended regulations.

The risk assessment for this supply was undertaken in December 2018, some eight years after it became a requirement. The local authority cited resource limitations, and other work being prioritised over statutory private water supplies duties for this not being carried out sooner. These limitations have continued, and have been exacerbated recently by staff absences, retirement of key experienced staff, and the unsuccessful recruitment of officers into these roles, along with the impacts of the pandemic.

The Inspectorate has found the same issues, along with a lack of training, to be commonly given explanations by local authorities for not meeting their statutory private water supplies duties. Local authorities often find themselves having to manage limited resource, and utilising resource best they can to manage a range of competing statutory duties.

In December 2018 the local authority took a representative sample from the kitchen tap of one of the dwellings fed by this supply. The property was supplied by a pipe that branched off the main supply pipe via a storage tank located in a field above the premises. A range of parameters were tested. Although the water was visually clear, taste and odour free, samples contained faecal indicators (see results in table below), which was confirmed by Public Health England (now UKHSA) to represent a potential danger to human health. The risk assessment (completed on the same day) identified that the condition of this tank was poor, inadequately sealed, and generally unfit for purpose. As there was no treatment further downstream of the supply, the local authority considered this to present a potential risk to health. The risk assessment also identified failure by the management company to adequately maintain and disinfect the supply, or to keep and make available to the local authority, records of its management and maintenance.



Parameter standard


>100 in 100ml

0 in 100ml

Escherichia Coli

>78 in 100ml

0 in 100ml


43 in 100ml

0 in 100ml

Clostridia Perfringens

43 in 100ml

0 in 100ml

Sulphite-reducing clostridia

43 in 100 ml

0 in 100ml

Restriction of use advice (boil water Notice)

In response to these findings, the local authority emailed the managing agents instructing them to inform the occupiers of all properties affected to boil the water prior to consumption. The occupier of the property from where the failed sample was taken was also notified by telephone. The results and the advice to boil the water was further communicated to consumers in hard copy letters which were posted to each property. The letter advised that the water should be boiled before consumption until otherwise informed.

These risks were brought to the attention of the managing agent in writing by the local authority, who were tasked to carry out an investigation to include an inspection of the raw water catchment and source, any treatment processes, the distribution network including any tanks, pipework, and fittings and to give due consideration to taking alternative sampling points throughout the water supply system. Such an investigation must be initiated by the local authority under the requirements of regulation 16 of the Regulations when it suspects that a private water supply is unwholesome.

The managing agent in turn gave an informal commitment to undertake the necessary remedial work to mitigate the risks. The local authority did not serve a notice to require the improvements but placed an expectation on the managing agent to complete the work in a timely manner. This was not compelled by means of enforcement. The Inspectorate has found that it is common for local authorities to enter into informal agreements of this nature, instead of initiating enforcement action, as is required under regulation 18.

Regulation 18 of the Regulations requires that where a potential danger to human health is identified on a private supply, a local authority must serve a notice to restrict the supply and to specify the actions necessary to restore the quality of the water.

No further site visits were made to this supply by the local authority between January 2019 and November 2021. The ability for them to do so being greatly impeded in 2020 by the pandemic restrictions. Even when restrictions were relaxed, work pressures and conflicts of other priority work meant a return visit was not possible until November 2021. During this three-year period, consumers continued to boil their water before consumption.

Revisit and investigation

In November 2021, when the local authority returned to site, they found that none of the remedial work, which they had informally committed the managing agents to three years earlier, had been completed. Further samples were taken and the danger to human health was again verified by the presence of faecal indicator parameters in samples taken. The local authority again sent hard copy letters to all relevant persons instructing them of the need to boil the water for consumption. At this stage the local authority consulted the Inspectorate’s website guidance with regard any enforcement obligations they might have. Unfortunately, the information provided on the main website page at this time (not Information note itself) was incorrect, in that it stated that the serving of a regulation 18 notice was a discretionary power, which it is not (although this is the case where a supply is unwholesome but not a danger to human health). Unfortunately, this error led again to enforcement not being initiated. This website inaccuracy was corrected immediately, once it had been pointed out by the local authority. On 15th November 2021, the local authority took a further sample from a kitchen tap of a different property on the supply. This was taken in response to a request by one of the consumers (a property tenant) who lived on a different branch of the supply to those where samples had previously been taken. It was not being fed via the afore mentioned poorly sealed and deficient tank. However, despite this, and even though the water was flowing through a UV disinfection unit located at this property, faecal bacteria were detected in this sample. The local authority concluded that the cause of this was the UV unit not being adequately maintained or regularly serviced to the manufacturer’s instructions.

Regulation 18 notice

On 26 November 2021 the local authority served a regulation 18 notice on the managing agents and the landowner. A copy of the notice was also provided to occupiers served by the supply. A copy of this was sent to the Inspectorate as per the reporting requirements of regulation 14.

Inspectorate involvement

On 30 November 2021 one of the consumers served by this supply contacted the Inspectorate to raise their concern over the way in which the local authority had managed the contamination of the supply and to request an independent Inquiry. The Inspectorate advised that it had no legislative power or remit to carry out an Inquiry, but the enquirer could make a formal complaint to the local authority’s ombudsman. The Inspectorate did however provide the enquirer with guidance on the requirements of the regulations and outlined the duties that local authorities had under this legislation.

The Inspectorate also contacted the local authority to firstly, inform them of the concerns raised by the enquirer, secondly, better understand the context of the issues raised, and thirdly provide guidance on the regulations where it believed the local authority may have fallen short of the requirements. This discussion revealed that whilst a regulation 18 notice had been served in recent days, a potential danger to health had been known about since 2018. During this three-year period consumers had been advised to boil the water to protect their health.

Unfortunately, one household had not, until very recently, been aware of this long-standing restriction of use and the reason why it had been put in place three years earlier, as this had not been communicated to him when the tenancy started. The knowledge that they had been consuming contaminated water for such a protracted period was now causing them material distress. They believe that failings by the local authority, and their landlord were the root cause of alleged sickness, which had been ongoing since they moved into the property.

This case study highlights some of the additional risks that long term restrictions of use can result in. Here miscommunication and errors by different stakeholders led to consumers being exposed to various hazards over an overly extended duration. These can have undesirable consequences. Sometimes managing these situations can be difficult for local authorities, due to conflicting priorities, lack of training and resource. In this case the Pandemic caused unforeseen delays, which were out of the control of local authorities.

Nevertheless, restrictions of use should only be used for temporary periods whilst a long-term fix is underway. Boil water notices are not a sustainable or sensible solution to existing microbiological risks. Research has shown that these are not universally followed by consumers. Routinely boiling water introduces an increased risk of domestic injury to the users via scalding. They should only ever be used as an emergency measure of short duration.

This case study demonstrates that where a danger to health has been identified, it is necessary to initiate enforcement as soon as it is known and practicable. This commits the relevant person(s) to legally binding remedial steps to a specified timetable with penalties if not completed. Informal arrangements do not necessarily ensure that the required actions are delivered. Furthermore, restrictions of use over long period can mean that the risk of advice to protect human health being overlooked by some, miscommunicated, forgotten or ignored may increase with time.


The managing agents have since initiated a programme of works to improve the supply, including the installation and servicing of UV treatment systems. On 2 February 2022 further sampling was undertaken to verify the quality of the supply post remedial work.

Recognising a need for additional resource and in house expertise in the regulation of private water supplies, the local authority has since recruited a suitably experienced consultant to assist with private water supply risk assessment duties.