Water Supply (Water Quality) Regulations 2010 (S.I. No. 994 (W.99) of 2010).

These Regulations implement provisions of Council Directive 98/83/EC on the quality of water intended for human consumption. They concern principally public control on and monitoring of water quality of water intended for human consumption.
The Regulations, among other things: require water undertakers to identify annually the water supply zones that are relevant for the purposes of the application of provisions of the Regulations; prescribe standards and values of wholesomeness in respect of water that is supplied; define monitoring regimes and define requirements in relation to the monitoring of drinking water abstraction points; provide rules for the treatment of water and regulates the substances, processes and products that may be used by water undertakers in connection with the supply of water; impose certain duties on water undertakers and local authorities; provide for enforcement; define offences.