It shall be the duty of the Secretary of State to secure that such appointments are made under this Chapter as will ensure that for every area of England and Wales there is at all times both—
Subject to the following provisions of this section—
shall have power, by notice to a company holding an appointment under this Chapter, to terminate the appointment or to vary the area to which it relates.
The appointment of a company to be a water undertaker or sewerage undertaker shall not be terminated or otherwise cease to relate to or to any part of any area except with effect from the coming into force of such appointments and variations replacing that company as a relevant undertaker as secure either-
An appointment or variation replacing a company as a relevant undertaker shall not be made in relation to the whole or any part of the area to which that company's appointment as water undertaker or, as the case may be, sewerage undertaker relates except where—
The conditions are that—
The Secretary of State may, after consulting the Authority, make regulations amending subsection (5)(a) above by substituting, for the quantity of water for the time being specified there, such smaller quantity as he considers appropriate.