Guidance documents

Information note on Regulation 16 (Wales)

For a printable copy see: Regulation-16-Walesv3-final-1.pdf (

Regulation 16 (Maintenance of records)

Under the Private Water Supplies Regulations (Wales) 2017, local authorities are under a statutory duty to provide certain information relating to private water supplies to the Welsh Ministers. The Drinking Water Inspectorate collates and reports this information on behalf of Welsh Ministers. The information kept by the local authority and the Inspectorate does not constitute a public register.

Regulation 16 requires each local authority to maintain a record of all private water supplies in its area. The required details of the supply to record are set out in schedule 5 of the Regulations, and also for reference in Annex 1 of this note. All private water supplies must be registered with the local authority. If a relevant person fails to register a supply, a local authority can serve a notice under section 85 of the Water Industry Act 1991, requiring them to do so, and setting out the details they require. See Annex 2 of this note.

All private water supply records must be kept for a minimum of 30 years.

Every year local authorities are required to review and submit details of each private water supplies in their area to the Drinking Water Inspectorate by 31 January via the annual data return. The Inspectorate will provide a template each year to facilitate this. The data return should include the status, changes of circumstance and records for every private water supply during the preceding year.

During the year, local authorities should note any significant change in circumstances as they happen, for example, revised risk assessment, deteriorating or improving trends in monitoring sample results. Key changes such as installation or upgrading of a of a new treatment process for larger supplies) should be noted, especially if these impact upon the risk assessment of the supply.

Annex 1

  • The name of the supply, together with a unique identifier.
  • The type of source. There are three categories of sources: (1) surface waters (rivers, streams, lakes, reservoirs); (2) groundwaters (springs, wells, boreholes) that are not influenced by surface waters; and (3) mixed sources which are groundwaters that are influenced by surface water. For groundwater the geological strata should be recorded.
  • The geographical location using a 12-figure ordnance survey grid reference (Easting and Northing) of the location of the source, as close as possible to its known location.
  • An estimate of the number of people served by the supply.
  • An estimate of the average daily volume of water supplied in cubic metres (using 0.2m3/day per person, which is 200 litres per person per day).
  • The type of premises supplied (for example, private domestic dwellings, hotels, bed and breakfast establishments, schools, colleges, hospitals, public libraries, food production undertaking).
  • Detail of any treatment process, together with its location (examples of treatment processes include collection chambers, blending, coagulation and flocculation, clarification, settlement, sedimentation, aeration and oxidation, filtration, ion exchange, membranes, disinfection).
  • The name of the region of Public Health Wales in whose area the supply is located.

Annex 2

Schedule 5 states the local authority is also required to include in the record for each private water supply within 28 days of the information being available, the following:

  • A plan and description of the supply – this schematic plan forms part of the risk assessment and should show/describe the source, the treatment and distribution network (including inspection chambers or storage tanks). The local authority will need to liaise with the supply owner or operator to obtain this, if not already provided.
  • The monitoring programme for the supply – number of samples planned for the year, number of samples taken during the year and whether supply closed/or was no longer in operation or new supply sourced during the year.
  • The date, results and location of any sampling and analysis relating to that supply, and the reason for taking the sample – routine programmed compliance sample (distinguishing whether the sample is a Group A or Group B monitoring sample), because of the risk assessment, investigation of failure, request from owner/occupier, complaint or operational incident.
  • The results of any investigation (of a failure to meet a standard or indicator parameter value) undertaken in accordance with the Regulations – whether the supply has been determined as a potential risk to human health or not, and whether there is an informal or formal action plan.
  • Any notices served under section 80 of the 1991 Act or regulation 20 – brief details of the action required by the notice and whether the notice has been complied with by the date specified in the notice.
  • Any action agreed to be taken by any person under the Regulations – whether agreed informally or by means of a notice.
  • Any request for the local authority to carry out sampling and analysis, undertake a risk assessment or give advice – including the reason for the request, such as complaint, prospective house purchase, complaint from a tenant.
  • A summary of any advice given in relation to the supply (and who the advice was given to).
  • A summary of any risk assessment. Local authorities should therefore send to the Inspectorate a copy of the summary sheet, which is derived from the risk assessment tool on its completion, for each of its supplies that it has assessed as high or very high risk.

Local authorities must also record the risk rating of each risk assessment that it has carried out for the required calendar year as part of its annual data return to the Inspectorate. This rating should reflect the risk at the time of the annual return, not at the time the risk assessment was carried out. Therefore, in some instances, supplies that were assessed as high risk at the time of their inspection may well be medium or low risk by the time the data return is due (at the end of each January) following the completion, as verified by the local authority, of the mitigating actions identified by the risk assessment.

  • A summary of the reasons for a decision to reduce or exempt altogether the monitoring of a particular parameter under part 4 of schedule 2 regulation 11(8A). For further details see Information note for regulation 7.

PWS (Wales) Regulations 2017 v.3, February 2021