Regulation 5

The purpose of Regulation 5 is to prevent the use of products or substances being used within a private water supply system that may have a detrimental effect on the safety or quality of drinking water. Any product used within such a system must have documentation demonstrating that prior to use checks were undertaken to ensure that the product or substance conforms to the requirements of this Regulation.

Regulation 5

Regulation 5 (Wales)

The documentation should be provided by the manufacturer or supplier of the chemical or material on installation and the relevant person(s) of the supply should then be able to produce this documentation to the local authority during the risk assessment process.

The scope of Regulation 5 applies to products and substances in use after 1 January 2010 (or 26 May 2010 in Wales). Products in place prior to these dates are still permitted to be used however; if maintenance is required on these products then any material used must comply with Regulation 5.

Approving a Product

If a product or substance has gained Regulation 5 approval then it will be included in the transitional list of approved products. In order for a product/substance to be included on this list then the manufacturer or supplier must be able to show that the product or substance has been used, in at least three different private water supplies for a period of 12 months, prior to the date of application

To apply for Regulation 5 approval then a Regulation 5 Application form will need to be completed and returned to DWI:

Regulation 5 Application form

Small Surface Area

There are some products where contact with the water is so minimal; the product is unlikely to adversely affect the quality of the water supplied. These products are not required to gain Regulation 5 approval and examples of the types of product that are classified in this category are listed in the Advice Sheet 8:

Advice Sheet 8

The critical factors to consider are the volume of water, the surface area of the product that is in contact with the water and the contact time between the water and the product.

Conformity to BS EN Standards

Some chemicals which already conform to a BS:EN standard (See Annex 2 of SoS list) can be used within private water supply systems without the need for any approval however these chemicals will be need to be dosed in accordance with any national conditions of use.

List of Approved Products

Action to Take for Local Authorities

Local authorities should be satisfied that any products and/or substances in use within a private supply are documented as part of any risk assessment, any investigation or any improvement works.

If, as part of an investigation or remedial works, it is suspected that a product has been used which does not satisfy the requirement of Regulation 5, the local authority should advise the relevant person(s) that the use of the product or substance is in breach of the Regulations and steps will need to be taken to install or use an alternative approved product:

Approved products

If the breach is sufficiently serious that either the supply is a potential danger to human health or is unwholesome then the local authority should serve the appropriate notice. However the local authority does have the ability to provide advice and negotiate an agreeable timescale for all parties to secure improvements.


Regulation 5 applies to the approval of all products used both before and at the treatment works and in water distribution systems up to the point of delivery to premises. Products used in water systems within properties are subject to approval by the Water Regulations Advisory Scheme (WRAS). Further information on these products and on WRAS can be found on their website at

Back to top