The Public Water Supplies (Scotland) Regulations 2014

Treatment of raw water

29.—(1) Subject to paragraph (3), before providing a supply of water for human consumption purposes, Scottish Water must ensure that the water is—

(a) subjected to sufficient preliminary treatment;

(b) disinfected; and

(c) subjected to an adequate treatment process.

(2) Scottish Water must—

(a) design, operate and maintain the disinfection and treatment process so as to keep disinfection and treatment by-products as low as possible without compromising the effectiveness of the disinfection or treatment; and

(b) verify the effectiveness of the disinfection and treatment process.

(3) Where the Scottish Ministers confirm, by notice given to Scottish Water, that they are, in respect of a supply of water specified in the notice (“the specified supply”), satisfied that—

(a) Scottish Water was, or is (for such period as may be specified), unable to comply (in part or otherwise) with paragraph (1) without causing an interruption of the specified supply;

(b) bearing in mind the risks to human health which would be caused by any such interruption, to protect human health, the specified supply should not be interrupted; and

(c) other action (which would not interrupt the specified supply) will be, or has been, taken by Scottish Water to protect human health until it is able to comply with paragraph (1),

Scottish Water may provide the specified supply without complying with paragraph (1).

(4) Where, by virtue of paragraph (3), Scottish Water provides a supply of water for human consumption purposes which does not comply with paragraph (1) it must, notwithstanding paragraph (3), comply with the other requirements of these Regulations (including taking such action as is necessary to ensure that the supply satisfies the requirements of regulation 4(2)).

(5) Scottish Water must, before (or, in so far as it is not reasonably practicable to do so, promptly after) providing a supply of water for human consumption purposes which does not comply with paragraph (1), inform (in so far as it has not already done so) those of its consumers to whom it supplies the water—

(a) that the water has not been subjected to sufficient preliminary treatment, disinfected or, as the case may be, subjected to an adequate treatment process;

(b) of other action that has been taken, or will be taken, to ensure that the supply satisfies the requirements of regulation 4(2); and

(c) of the action (if any) that Scottish Water considers is necessary or desirable for the consumer to take to protect human health.

(6) Paragraph (1) does not require Scottish Water to disinfect such groundwater as the Scottish Ministers may, by notice given to Scottish Water, specify.

(7) For the purposes of this regulation—

(a) “adequate treatment process” means a continuously operated process of blending or purification treatment which removes, reduces or renders harmless any micro-organism, substance or parasite in, or property of, water, so that the water does not constitute a potential danger to human health;

(b) “sufficient preliminary treatment” means the treatment necessary (if any) to—

(i) remove or reduce the value or concentration of any property or substance which would interfere with disinfection; and

(ii) reduce turbidity to less than one Nephelometric Turbidity Unit; and

(c) water is supplied for human consumption purposes when it leaves a treatment works.