(FAQ7) Do products used only in contact with treatment chemicals need to be approved under the regulations?


From time to time the Drinking Water Inspectorate (DWI) receives requests for advice from manufacturers and suppliers of tanks, pumps and associated pipework, who have been told by plant designers, civil engineers, or even by Water Supplier’s staff that these products must conform to the requirements of relevant regulations .

The test methods used to evaluate the suitability of materials and products for use with drinking water (BS 6920/WRAS tests of effect on water quality, and the leachate studies specified by DWI) are not designed for use with materials and products in contact with treatment chemicals.

Products covered by the regulations

In addition to chemicals that may be used in the treatment of drinking water supplies, the relevant regulations cover construction products which may be introduced into contact with water. Products which are introduced into contact with drinking water need to conform with the appropriate requirements of relevant regulations, and these products may, of course, also come into contact with treatment chemicals.

Some tanks, pumps and associated pipework etc. may, however, never be introduced into contact with water and will only be used in contact with the appropriate treatment chemical(s). In this case approval under the relevant regulations is not given and DWI does not consider these products.

Fitness for purpose

DWI will assume that the users of any products that will be in contact with treatment chemicals will, nevertheless, have satisfied themselves about the compatibility/fitness of the materials of construction for use with the chemicals in question.


  • such products will not be considered by the DWI unless they will also be used with drinking water
  • the normal test requirements (under the relevant regulations) are not necessarily applicable or suitable for use with products in contact with treatment chemicals only
  • users of such products have the right to satisfy themselves that the materials used to make these products will be compatible with the treatment chemicals that will be in contact with them – this might involve testing, but any such testing is outside the remit of the relevant regulations and we are unable to comment upon any tests requested by users
Back to top