Numbers of samples
9.—(1) Subject to paragraph (2), in each year a water undertaker must take, or cause to be taken—
(a)from its sampling points; or
(b)to the extent authorised by or under regulation 8, from its supply points, the standard number of samples for analysis as regards residual disinfectant and each parameter listed in column (1) of Table 2 in Schedule 3 or, as the case may be, Table 3 in that Schedule.
(2) Where, in respect of a parameter subject to check monitoring—
(a)a water undertaker is of the opinion that the quality of water supplied to a water supply zone which it supplies is unlikely to deteriorate; and
(b)in each of two successive years the results of samples taken, subject to paragraph (3), in accordance with these Regulations show no significant variation and—
(i)if the parameter is colony counts, have shown no abnormal change;
(ii)if the parameter is hydrogen ion (item 9 in Table 1), have established a pH value that is not less than 6.5 and not more than 10.0;
(iii)in any other case, have established a concentration or value for that parameter that is significantly lower than the prescribed concentration or value, or specification,
the number of samples to be taken in the following year for that parameter may be the reduced number.
(3) Samples required to be taken by this regulation must be taken at regular intervals.
(4) In this regulation—
(a)in relation to sampling points, residual disinfectant or a parameter and the supply of water to an estimated population within one of the ranges shown in column (2) of Table 2 in Schedule 3, “the standard number” and “the reduced number” means the number shown in column (4) and column (3), respectively, of that Table as applicable to that substance or parameter by reference to a population within that range;
(b)in relation to supply points, each of the parameters specified as items 7, 8 and 9 to 25 in column (1) of Table 3 in Schedule 3, and the supply of a volume of water within one of the ranges shown in column (3) of that Table, “the standard number” and “the reduced number” means, subject to sub-paragraph (c), the number shown in column (5) and column (4), respectively, of that Table as applicable to that parameter by reference to a volume supplied within that range; and
(c)where a particular supply point is in use for part only of a year, “the standard number” and “the reduced number” means the number that bears to the number shown in column (5) and column (4), respectively, of Table 3, the same proportion as the number of days in that year in which the supply point has been in use bears to 365.