129.—(1) It shall be the duty of each water undertaker to comply with any arrangements entered into by it under Article 126(1).
(2) Where, pursuant to any such arrangements, the fluoride content of any water is increased, the increase may be effected only by the addition of one or more of the following compounds of fluorine—
(a)hexafluorosilicic acid (H2SiF6);
(b)disodium hexafluorosilicate (Na2SiF6).
(3) Subject to paragraph (4), water to which fluoride has been added pursuant to any such arrangements entered into by a water undertaker (with a view to its supply in an area) may be supplied by that or any other undertaker to premises in any other area (whether or not that other area is the subject of arrangements under Article 126(1)).
(4) Paragraph (3) applies if (and only if) the undertaker or undertakers concerned consider that it is necessary for the water to be supplied in the other area—
(a)for the purpose of dealing with any serious deficiency in supply; or
(b)in connection with the carrying out of any works (including cleaning and maintenance) by the undertaker concerned or, as the case may be, by the undertakers concerned.
(5) In paragraph (4) “serious deficiency in supply” means any existing or threatened serious deficiency in the supply of water (whether in quantity or quality) caused by an exceptional lack of rain or by any accident or unforeseen circumstances.
(6) Arrangements entered into under Article 126(1) with a water undertaker shall remain in force until DHSSPS terminates them by order.
(7) An order shall not be made under paragraph (6) unless—
(a)DHSSPS has consulted the water undertaker in question; and
(b)a draft of the order has been laid before, and approved by resolution of, the Assembly.