(1) No person shall install, or cause or permit to be installed, on any service, any tap or flushing valve unless such tap complies with the requirements of S.A.B.S. 226, Water taps or such flushing-valve has been tested and has been approved by the local authority.

(2) Where such flushing-valves are used on supply-pipes connected directly to sanitary fittings, they shall be provided with a device which effectively prevents back-flow into the supply-pipe.