Private water supplies

Private water supplies are any supplies of water not provided by the public water supplier. In Northern Ireland less than one per cent of water comes from private water supplies. The DWI monitors private water supplies to ensure they meet standards set within the regulations.

Register of Private Water Supplies

The DWI holds a register of all known private water supplies in Northern Ireland that come under the Private Water Supplies Regulations. The regulations apply to private supplies that serve more than one household for purely domestic purposes, or are used in commercial food and drink production.

To register a new private water supply, please complete and return the registration form:-

The register includes details on site location, description of the source, purpose for which the water is used, volume used, and any treatment of the supply.

Monitoring of Private Water Supplies

An annual monitoring programme is in place to check the quality of each registered supply. The frequency of the sample collection and the range of parameters (microbiological, chemical, or radioactivity) tested for are determined by the type of private water supply and the volume of water used or the size of the population served.

Flexibility is provided in legislation to reduce monitoring or to make a decision not to monitor if particular criteria are met. The monitoring programme is therefore reviewed and updated annually and reconfirmed at least every five years. Any reduction or removal of monitoring of selected parameters is based on historical sample results and information from site-specific risk assessments.

For radioactivity parameters a decision may be taken not to monitor for a period of time. In this circumstance a ‘Notice of Decision’  is required to publish this information. A Notice of decision detailing the reduction in monitoring frequency of Radon, Tritium and calculated Indicative Dose is available from 2018 to 2023. These parameters have been removed from the monitoring schedule for a period of five years. This time period will be reviewed in the event of any incidents or change of risk.

Single Private Well

If your private water supply is to a single private dwelling it is not required to be monitored by the Drinking Water Inspectorate. You can contact the environmental health department of your local council if you wish to have your supply tested. You can find contact details for your local council on nidirect.

To find out more about the potential risks to your single private well supply and to help identify measures you can take to reduce the risks and improve the quality of your well water please navigate to the Single Private Well Application to complete the short assessment.

DAERA iHub DWI Viewer

The location of private water supplies across Northern Ireland which have been registered with the Drinking Water Inspectorate under The Private Water Supplies Regulations (Northern Ireland) 2017 are available via the DAERA Information Hub (iHub) Drinking Water Inspectorate Viewer.

If you have trouble accessing or using the DAERA iHub for locating private water supplies please see our Accessibility Statement for further information and guidance.

Responsibility of the Owner/User

Owners/users of private water supplies have responsibility under the private water supplies regulations to supply water that is wholesome and safe to drink.

Where a supply is identified as not being safe or wholesome then following an investigation, remedial actions may be necessary to meet the drinking water quality standards.


A summary of the drinking water quality of registered private water supplies can be found in the DWI annual report:-

The following Drinking Water Quality tables provide detail of the number of samples of private water supplies within each council area where full compliance with the regulatory standards has not been met.

Enforcement Policy

If a private supply fails to meet the required standards, the DWI may take enforcement action as detailed in the Environment, Marine and Fisheries Group Enforcement Policy:-

Risk Assessment

The Regulations require a risk assessment to be carried out for each registered supply, covering the whole private supply system, from source to tap. These assessments are deemed the most effective means of consistently ensuring the safety of a drinking water supply and will identify areas where there may be potential contamination.


You can view the legislation relating to private water supplies at the link below:-

The Private Water Supplies Regulations (Northern Ireland) 2017

The above Regulations implement the Drinking Water Directive (98/83/EC), amending Directive (EU) 2015/1787 which revised the monitoring and analysis requirements in Annex II and Annex III of Directive (98/83/EC) and Directive 2013/51/Euratom in relation to private water supplies and the DWI is, for certain functions, facilitated by the Environmental Health departments of the district councils.

Guidance and Advice

If you own or use a private supply it is important that you are aware of the quality of the supply and the risks associated with it. Guidance and advice for owners and users is available from the following: 

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