Guidance documents

Roles and responsibilities

This page sets out the roles and responsibilities of health protection teams in the Drinking Water Inspectorate (the Inspectorate), United Kingdom Health Security Agency (UKHSA), Public Health Wales and local authorities in relation to private supplies in England and Wales.


Guidance was published in 2009 entitled ‘Drinking Water Safety; Guidance to Health and Water Professionals’. Its purpose was to provide clarity on the respective roles and responsibilities of the various agencies in relation to drinking water and the protection of public health.

In the interest of private water supply consumers, it is important that there is a close working relationship between the Inspectorate, water suppliers, health professionals, and local authorities is maintained to secure the safety and quality of drinking water on a day-to-day basis and also in relation to operational events and emergencies.

Roles and responsibilities of key organisations in relation to private supplies:

The Drinking Water Inspectorate:

The Inspectorate provides advice to local authorities on the scientific and technical aspects of the implementation of the Private Water Supply Regulations in England and Wales. Legislation and guidance can be found on the Inspectorate’s website. Local authorities are able to obtain advice on specific cases by contacting the DWI at

The Inspectorate is responsible for reporting on compliance with drinking water and reports are published annually. The Inspectorate is also a designated World Health Organisation Collaborating Centre on Drinking Water Safety and Regulation. As part of this work, the Inspectorate works closely with UKHSA to arrange for the development of health risk assessments and national guidance in relation to current drinking water monitoring parameters, standards and emerging issues. The Inspectorate also manages Defra’s research programme on Drinking Water Quality and Health.

The Inspectorate also has a statutory role under Section 81 of The Water Industry Act 1991 to confirm, with or without modification, any notice served by a local authority under section 80 of the Act, where an appeal to that notice by a relevant person has been submitted to the Secretary of State via that local authority.

The Inspectorate publishes a sampling manual for private water supplies. This forms part of an ISO/IEC 17024 scheme and is made available to local authority samplers or their representatives for the purposes of meeting regulatory monitoring standards. 

Local Authorities:

Local authorities have statutory duties under the provisions of the Water Industry Act 1991, Water Act 2003, the Private Water Supply Regulations (England) 2016, The Private Water Supplies (England) (Amendment) Regulations 2018, and The Private Water Supplies (Wales) Regulations 2017.

These duties include a requirement to risk assess the private supplies in their area to establish if they constitute an actual or potential danger to human health. Local authorities are not required to carry out risk assessments or monitoring on supplies to single untenanted dwellings, but they must do so when the building owner or occupier requests it. Local authorities are also responsible for arranging monitoring of private supplies in their area to determine compliance with the drinking water standards. Where a failure of a drinking water standard is reported then the local authority must investigate to determine the cause and take appropriate action to secure that relevant persons rectify any deficiencies identified.

Local authorities are advised to contact UKHSA if a public health threat is suspected or confirmed, including any outbreak of illness linked to a private supply. It is the responsibility of the local authority to ensure that any such advice is current and still valid for use.

The United Kingdom Health Security Agency (UKHSA) and Public Health Wales:

The UKHSA and Public Health Wales exist to help protect the public against infectious disease, hazardous chemicals, poisons and radiation.

Nationally, there are a number of experts in UKHSA and Public Health Wales who can advise on the potential public health risks from microbiological or chemical contamination.

Locally, UKHSA and Public Health Wales teams support the work of local authorities in relation to the safety of drinking water supplies; however, they have no formal statutory duties and powers under the Private Water Supply Regulations. UKHSA and Public Health Wales are likely to be approached by local authority staff for advice and support regarding the results of testing of private supplies and whether they represent a risk to human health. The health and toxicological advice required in these situations should be no different to that provided in response to similar enquiries about the results of testing of public water supplies. Health protection staff are not legally responsible for determining whether a particular private water supply is a potential danger to human health – this is a matter which is determined by local authorities and is based on detailed knowledge of the supply from source to tap obtained from historic monitoring information, risk assessments and investigations carried out in conjunction with the private supply owner and, where appropriate, the local water supply company and the Environment Agency.

In relation to outbreaks of illness or other public health emergencies, then health protection staff have a more active role and will carry out a wider health risk assessment with the assistance of specialist units within the UKHSA or Public Health Wales and, if appropriate, an epidemiological investigation. When carrying out this role health protection staff may require information from local authorities about private water supplies and from water companies about public water supplies. Depending on the severity of the incident, health protection staff will set up and lead an incident management team to coordinate the health protection response. In the event of a major emergency, UKHSA or Public Health Wales will lead a Scientific and Technical Advisory Cell (STAC) feeding directly into the wider Incident Management Team. Further details on how this works in relation to a water emergency can be found from the UKHSA or Public Health Wales.