Specifies general constructional and performance requirements for electric storage water heaters of 25-litre to 630-litre rated hot water delivery. (Requirements for gas-fired water heaters are specified only by reference to Codes AG 102 and AG 109 published by AGA/ALPGA.) In the interests of energy conservation, specifies reduced allowable heat loss and the provision of user-adjustable means of temperature control (alternatively the capability to be modified to achieve this control). Specifies hydraulic tests and standard methods of measuring heat losses and hot water delivery, also routine and type test schedules.