Water Supply Industry Interpretations and Advice

  • Area of Interest : Backflow prevention
  • Topic : Fluid category
  • Title : Domestic appliances which comply with BS EN 61770
  • Clause Reference : Schedule 2 paragraph 15 (5)
  • Reference Number : B48
  • Decision Date : October 2011

The backflow protection arrangements and suitability of materials in contact with drinking water requirements identified in BS EN 61770 do not satisfy the requirements of the Water Supply (Water Fittings) Regulations, Byelaws in Scotland. Therefore unless there is additional evidence to demonstrate conformity with the UK national requirements conformity with this standard will not be accepted as evidence of compliance.

Washing machines and dishwashers installed in domestic premises that comply with BS EN 61770 but which have not been assessed against the Regulators’ Specification for the prevention of backflow are categorised as a fluid category 3 risk. That is to say a double check valve, or an equivalent device, providing at least fluid category 3 backflow protection must be installed on all pipework supplying or intended to supply drinking water to these appliances.

In the event that these appliances satisfy the Regulators’ Specification for the prevention of backflow but the suitability of any hoses supplying the appliance or non–metallic components (upstream of the backflow protection) has not been proven the installation will still be considered a fluid category 2 risk. In these circumstances the system must be supplied via a single check valve or an equivalent device providing at least fluid category 2 backflow protection.