Section 144A of the Water Industry Act 1991 enables a consumer to serve notice electing for charging for the water supply to his home by reference to volume. Section 144B of the Act restricts a water or sewerage undertaker from beginning to fix such charges by volume without the consumer's consent or unless there has been a change of occupation. These Regulations prescribe additional conditions which must be satisfied before a consumer may revoke his election, and before a relevant undertaker can be restricted from requiring a change in the basis of charging under section 144B. The conditions are that: (a) in the case of premises which are not used solely as a person's home, that other use is not the principal use of the premises; (b) the water supplied to the premises is not used specified. and (c) the premises are not in an area which has been determined by the Secretary of State to be an area of water scarcity for the purposes of these Regulations under regulation 3.