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BS 6920 Testing DWI Regulation 31 Consultancy Home
Water Regulations Advisory Scheme (WRAS)
On 1st July 1999 the Water Byelaws in the UK were replaced by Regulations - The Water Supply (Water Fittings) Regulation 1999. For many years the Water Byelaws Scheme (WBS) Tests of Effect on Water Quality had been used to assess the suitability of materials for use with drinking water, but they have been replaced by the Water Regulations Advisory Scheme (WRAS).  
Copies of the new regulations can be obtained from either Her Majesty's Stationery Office (HMSO) or downloaded from the internet from the HMSO website. Compliance with WRAS requirements will be demonstrated if the material has met the full requirements of BS 6920 or the material has been tested satisfactorily to the requirements of another set of equivalent test requirements covering the same areas of concern as BS 6920.

Alternative Test Requirements
Components which have been tested to the comprehensive national requirements currently in force; eg. results from The Netherlands, France or Germany can be considered to meet WRAS requirements if -

  • the test surface area to volume ratio used is equal to or more severe than that applicable to the proposed use of the component
  • the test conditions (method of sample preparation and temperature of extract preparation) relate to the proposed use of the product
  • the tests carried out cover, as a minimum, assessments of the ability of the component to affect the odour and flavour of the water, leach metals into the water, and support the growth of microorganisms in the water

Demonstration of Conformity

  • This can only be demonstrated on the basis of the full test report, including the surface area to volume test ratio and the full results of the test undertaken
  • The tests undertaken must include an odour and flavour test, leaching of metals and a microbial growth assessment
  • Unless the tests have been undertaken at a test ratio of 150 cm2/litre, i.e. 15 000mm2, (the current BS 6920 test requirement) or greater, they cannot give a basis for the listing of the product in the materials section of the WRAS Water Fittings and Materials Directory.

Thames Water Utilities 2005