Private Water Supplies - Case Study

Deficiencies in water supplies on new housing developments


In April 2023 the Inspectorate was made aware of an MP’s letter regarding an ongoing water supply problem at a new housing estate in her constituency. The residents had been without a reliable supply of safe drinking water for the past ten months causing distress to those affected. The supply of water to the estate was reported as being “not of drinking water quality” following recent testing. The Inspectorate investigated and established what action the local authority had taken to facilitate a safe and sufficient supply of drinking water to the estate.


The Inspectorate learnt that planning for the residential estate had been granted by the local authority ten years earlier. Planning applications in England and Wales do not include a requirement for a wholesome and sufficient supply of drinking water as part of the approval process, so the planning consent did not include the provision of a potable water supply.

The Inspectorate found that the current borehole was the fourth to be trialled since planning for housing development had been granted, the other three having been rejected due to poor water quality or insufficiency risks. The latest was, at the time of correspondence, being pumped to waste in anticipation of the water requiring minimal, if any, treatment. The housing developer had also taken additional action by securing a contingency plan to provide a supply of off-site water via tankers if this latest arrangement, or the borehole itself, failed.

No legal obligation exists for borehole installers or those that commission them to notify local authorities.

Temporary supply arrangements

This temporary supply had been tested and risk assessed by the local authority and considered by them to be sufficient and wholesome. As such, they had not served any notice to require improvements, on the basis that none were necessary at that time. The Inspectorate concluded that the local authority had met the requirements of its regulatory duties and that consumers were not at risk, at least whilst the temporary supply was in place. It also concluded that the developer’s difficulty in establishing a suitable borehole after four trial attempts posed a risk to reaching a long-term viable solution.

It was therefore essential that the local authority conducted a robust source to tap risk assessment of any potential new supply, including a detailed assessment of the likelihood of insufficiency, taking account of climate change, local hydrogeology, consumer demand and any future expansion of the estate. Contingency arrangements in the event of any planned or unplanned insufficiency must also be put in place.

Key points

This case study illustrates well the inevitable risks to consumers that are likely to arise from the following specific gaps in legislation in relation to private water supplies. In addition to public health risks, disputes between the parties concerned may also result from these. These must be dealt with by legal professionals as civil matters, as they are not covered by private water supply legislation. This can be costly and may deter some people who cannot afford the costs of such measures.

  1. There is currently no obligation in law to ensure that a wholesome and sufficient private water supply is considered as part of a planning application to a local authority. Neither is there a requirement in the planning application process for local authorities to assess potential insufficiency, or any water quality impact, on any existing private water supply consumers, where a new private water supply is being planned for a new development (where it may share or affect the source aquifer).
  2. There is no requirement as part of the property conveyancing process that the Law Society manages, that requires solicitors to ascertain that properties have an adequate provision of wholesome and sufficient water supplies.
  3. There is no obligation for any private water supply – new or existing – to be registered with the relevant local authority. This will lead to these supplies being unregulated until they become known to the local authority, which may never be the case.

Whilst these deficiencies in the legislation exist, unsuspecting consumers are potentially at risk of receiving inadequate or failing private water supplies, where these circumstances arise.

Defra response

The Secretary of State replied to the MP concerned with the following key points:

  • This matter was largely a civil matter, which the Secretary of State was unable to comment on.
  • Any supply from someone other than a water undertaker or licensee properly authorised under the Water Industry Act 1991 (‘the Act’), including temporary ones, must be regulated under the Private Water Supplies (England) Regulations 2016 (as amended) (‘the Regulations’).
  • Where there is a risk of a supply becoming insufficient on a longer-term basis then the local authority may consider whether s.79 of the Act is applicable, which would require the relevant undertaker to provide a supply of water to the consumer by a means other than by use of its water pipes.
  • in the event of a sufficient and wholesome borehole being installed, the local authority has duties under regulations 7 to 14 of the Regulations, including the requirement to conduct a risk assessment, put in place a monitoring programme, and to act where required. There may also be a power to recover the costs of carrying out some of these functions.
  • A private water supply must not be brought into use or used until the local authority is satisfied that the supply does not constitute a potential danger to human health.
  • To secure a permanent, non-private water supply, residents may also want to consider whether it is feasible for them to connect their properties to a mains supply at cost. This would involve further discussion with the developer and the water undertaker with responsibility for the provision of a public water supply in their area.