Guidance documents

Information note on Regulation 15 (Wales)

For a printable copy see: Regulation-15-Walesv2-final-1.pdf (

Regulation 15 (Requirement to risk assess and monitor a new supply or a reinstated existing supply)

This regulation concerns the requirement to risk assess and monitor:

  • A new private water supply.
  • A reinstated existing supply (after 12 months of non-use).
  • A previously abandoned source or disused source brought back into supply for domestic purposes.

As soon as a local authority becomes aware, of any new private water supply or reinstatement after 12 months non-use, in its area, (whether a regulation 8, 9, 10 or 11 supply) it must contact the relevant person to determine if the supply is to be used for domestic purposes. If so, the local authority should update its records accordingly. The supply should not be put into (re)use until the local authority has completed a regulation 6 risk assessment and determined monitoring requirements in accordance with either regulation 8, 9 or 11 as appropriate. Thereafter the requirements of regulations 6-14 and 16-19 apply, ie for all supplies1.

The person (re)commissioning the supply must also be made aware of any potential risks to human health identified by that risk assessment. Such risks will need to be mitigated by appropriate remediation before the supply can be put into use. A regulation 20 notice confirming the restriction of use of the supply, and any relevant remedial action required to mitigate the risk, must be served.

If the supply is not, or is likely not to be, wholesome or sufficient, a section 80 notice must be served on the relevant person after the supply has been brought into use.

The above actions must also be taken whenever a local authority becomes aware, that a supply used historically only for non-domestic purposes (for example, irrigation, horticulture, garden watering, vehicle washing, livestock welfare) is being used, or is likely to be used, for domestic purposes (such as drinking, cooking, food preparation, food production, personal washing or laundry). A risk assessment must be carried out and monitoring regime determined in accordance with the regulations.

Staff dealing with planning applications should have procedures in place to identify premises served by private water supplies to ensure that no planning application is granted for any premises that is to obtain a supply of water for domestic purposes from a new or reinstated private supply before the supply has been risk assessed.

The supply must not present a potential risk to human health and all necessary details should be documented on the local authority private supply record. Local authorities can take the opportunity at this stage to ensure that appropriate legallybinding agreements have been signed up to by all relevant persons (as defined in section 80 of the Water Industry Act 1991). These documents should lay out the responsibilities of each relevant person in respect of maintenance and management of the supply, access rights, apportionment of costs and charges (including those for sampling and risk assessment), emergency plans including alternative supplies, etc.

New supplies to Single dwellings

In the case of all supplies to single dwellings, under regulation 10 a local authority may monitor the supply as part of this regulation and must do so if requested to do so by the owner or occupier. Regulation 6(3) also requires that a local authority must carry out a risk assessment only if requested to do so by the owner or occupier of that dwelling.

Where a local authority becomes aware of a new supply to a single dwelling, they should contact the relevant persons to assess if the new supply is likely to present a risk of unwholesome water or a potential risk to human health. Where it suspects that this is the case, regulation 18(1) requires that a local authority must carry out an investigation to determine the cause and that it must act in accordance with regulation 18(3-5).

Timescales for acting under Regulation 15

Since new supplies cannot be used until the local authority is satisfied by means of risk assessment and monitoring that the supply is not a risk to human health, local authorities must ensure that these activities are carried out promptly. No timescale for completion has been set in the Regulations beyond that the time taken must be ‘as soon as is reasonably practicable’. Local authorities should be aware therefore of the need to set and publish a target that informs owners and managers of supplies of the likely timescale. It should be made clear in advance of the person(s) commissioning the new supply or reinstatement that they may be required to act to address any deficiencies identified by the local authority before the supply is brought into use.

If the relevant person chooses to put a new or reinstated supply into use before the local authority is satisfied there is no potential danger to human health, then the local authority must serve a notice under regulation 20. This should detail the restriction of the supply until such time that the local authority is satisfied that appropriate mitigation measures, as stated in the notice, are in place, citing the reason in the notice as non-compliance with regulation 15(2).

1 Supplies other than a supply to a single dwelling not provided as part of a commercial or public activity or as part of a domestic tenancy.

PWS (Wales) Regulations 2017 v. 2, February 2021