(1)  Where entry to premises is required for the purposes of –

(a) maintaining a works for the supply of water under this Act; or

(b) constructing or maintaining a works for the management of water under this Act; or

(c) carrying out any addition or modification to any such works –

an authorised officer must give notice in accordance with this section.

(2)  For the purposes of subsection (1)  –

(a) not less than 7 days' notice is to be given to the owner or occupier; and

(b) the notice may authorise entry at such times and on such occasions as are specified in the notice during the period that is so specified as the period required for the construction, maintenance, addition or modification; and

(c) the period specified in a notice under paragraph (b) may be extended by giving a further such notice to the owner or occupier not less than 2 days before the expiration of that period.

(3)  Except as provided in this Act, where the entry is required for the purpose of carrying out a survey or investigation for, or in connection with, a works for the management or supply of water under this Act or for a purpose not mentioned in this section –

(a) not less than 3 days' notice must be given to the owner or occupier; and

(b) the notice may authorise entry at such times and on such occasions as may be specified in the notice.

(4)  An authorised officer may use reasonable force to enter on land or enter a building or structure on land –

(a) with the authority of a warrant issued by a justice of the peace; or

(b) if the officer believes, on reasonable grounds, that the circumstances require immediate action to be taken.

(5)  A justice of the peace must not issue a warrant under subsection (4) unless satisfied, on information given on oath –

(a) that there are reasonable grounds to suspect that an offence against this Act has been, is being, or is about to be, committed; or

(b) that the warrant is reasonably required in the circumstances.