11.—(1) Subject to paragraphs (2) and (3), in each year Scottish Water must take, or cause to be taken, from the point at which water leaves each treatment works which serves a water supply zone, the standard number of samples for analysis to determine—
(a)the concentration of residual disinfectant;
(b)whether water leaving the treatment works complies with the prescribed concentration or value for—
(i)coliform bacteria (item 3) in Table A;
(ii)Escherichia coli (item 4) in Table A; and
(iii)nitrite [F1(item 24)] in Table B (where the point of compliance is a treatment works);
(iv)colony count (item 5) in Table C; and
(v)turbidity (item 13) in Table C.
(2) Where, in each of two successive years, the analysis of samples taken in accordance with these Regulations establishes that—
(a)for coliform bacteria, Escherichia coli, nitrite or turbidity (as the case may be), the prescribed concentration or value has not been exceeded; or
(b)for colony count, there has been no significant increase in the count,
the number of samples to be taken in the following year in respect of that parameter from the point at which water leaves that treatment works may, subject to paragraph (3), be the reduced number.
(3) For coliform bacteria or, as the case may be, Escherichia coli, the reduced number of samples may be taken only if Scottish Water considers that—
(a)there is no foreseeable risk that the supply will exceed the prescribed concentration or value for that parameter; or
(b)the treatment works is designed to secure that, in the event of a failure of the disinfection process, water that has not been disinfected cannot enter the supply.
(4) Samples required to be taken by this regulation must be taken at regular intervals.
(5) Where a treatment works is in use for only part of a year, the number of samples that must, under this regulation, be taken during that year (from the point at which water leaves the works) may be reduced in proportion to the number of days in that year that the works has not been in use.
(6) In this regulation—
“the reduced number” means the applicable number (if any) in column (4) of Table 4; and
“the standard number” means the applicable number in column (5) of Table 4.
Textual Amendments
F1Words in reg. 11(1)(b)(iii) substituted (1.1.2023) by The Public Water Supplies (Scotland) Amendment Regulations 2022 (S.S.I. 2022/387), regs. 1(1), 5