12Use of sewers, etc., for removing water
(1)The appropriate authority may use for the discharge of any water pumped or found by them during the construction of the works any available stream or watercourse, or any sewer or drain of a relevant authority in or through whose area the works may be constructed or pass, and for that purpose may lay down, take up and alter conduits, pipes and other works and make any convenient connections with any such stream, watercourse, sewer or drain within the limits of deviation but—
(a)the appropriate authority shall not discharge any water into any sewer or drain vested in or under the control of a relevant authority except with the consent of the relevant authority and subject to such terms and conditions as the relevant authority may reasonably impose; and
(b)the appropriate authority shall not make any opening into any such sewer or drain save in accordance with plans approved by, and under the superintendence (if given) of, the relevant authority in whom the sewer or drain is vested and approval of those plans by the relevant authority shall not be unreasonably withheld.
(2)(a)Section 85 of the [1991 c. 57.] Water Resources Act 1991 shall apply to, or to the consequence of, a discharge under the powers of this section into any controlled waters within the meaning given by section 104 of that Act as if this section were not a local statutory provision for the purposes of section 88 (1) (f) of that Act.
(b)In the exercise of their powers under this section the appropriate authority shall not damage or interfere with the bed of any watercourse forming part of a main river or the banks thereof within the meaning of section 113 of the Water Resources Act 1991.
(3)The appropriate authority shall take all steps reasonably required to secure that any water discharged by them under the powers of this section shall be as free as may be reasonably practicable from any gravel, soil or other solid substance or oil or matter in suspension.
(4)Any difference arising between the appropriate authority and a relevant authority under this section shall be settled by arbitration.
(5)In this section“relevant authority” means Thames Water Utilities Limited, the National Rivers Authority or a London borough council.