The Water Supply (Water Quality) Regulations 1989

Frequency of sampling

13.—(1) Subject to paragraphs (2) to (9), in each year a water undertaker shall take from its sampling points or, as the case may be, its supply points, for analysis for testing for compliance with each parameter not less than such standard number of samples as is specified in Tables 1 to 6 in relation to the parameter in question.

(2) For the purposes of the application of paragraph (1) to the parameters listed in Table 1 or 2 or referred to in Table 5, a supply which consists of both ground water and surface water shall be deemed to be a supply which consists only of surface water.

(3) Where in each of three successive years the requirement mentioned in paragraph (4) below is satisfied in relation to a parameter listed in Table 1, 2 or 3 or referred to in Table 5 and the water undertaker is of the opinion that the concentration or value in respect of that parameter is unlikely to increase or, in the case of hydrogen ion, total hardness or alkalinity, decrease to any significant extent in the next following year, the number of samples to be taken in that year in respect of that parameter may be the reduced corresponding number:

Provided that this paragraph shall not apply where the following year is 1990 and shall apply where the following year is 1991 or 1992 with the modifications specified in paragraph (5) below.

(4) The requirement referred to in paragraph (3) above is that analysis of each sample taken in relation to the parameter in question in accordance with paragraph (1) has established–

(a) in the case of hydrogen ion, a pH value that is no less than 6.5 and no more than 8.5;

(b) in the case of total hardness or alkalinity (where water has been softened or desalinated), a concentration that is no less than 90 mg Ca/1 or 45 mg HCO₃/1, respectively; or

(c) in any other case, a concentration or value which is less than 50% of the prescribed concentration or value.

(5) Paragraph (3) shall apply–

(a) where the following year is 1991 as if it referred to 1990 instead of three successive years;

(b) where the following year is 1992 as if it referred to two years instead of three years;

(c) with the substitution of “and the Secretary of State has notified the undertaker that he” for “and the water undertaker”.

(6) The number of samples to be taken in 1990 in respect of any parameter may, if on the application of the water undertaker the Secretary of State so authorises, be such reduced corresponding number, if any, as is specified in relation to that parameter in the relevant Table.

(7) Where–

(a) the result of the analysis of any sample taken in accordance with paragraph (1) has established in relation to any parameter listed in Tables 1 to 5 that the prescribed concentration or value has been contravened; or

(b) as a consequence of any change in a water undertaker’s practices as regards the treatment of water (whether at a service reservoir, treatment works or otherwise), the undertaker is of the opinion that the prescribed concentration or value in respect of any parameter has been or may be contravened,

the number of samples to be taken in respect of that parameter–

(i) in the remainder of that year and the following year; or

(ii) in such longer or shorter period as the Secretary of State may specify by notice in writing given to the water undertaker,

in respect of that parameter shall, where an increased corresponding number is shown in relation to that parameter, be the number determined in accordance with paragraph (8).

(8) The number determined for the purposes of paragraph (7) is–

(a) for any whole year in the period the increased corresponding number; or

(b) for any other period the increased corresponding number multiplied by the number of whole months in the period and divided by 12; and, where the result is not a whole number, rounded upwards to the nearest whole number.

(9) Where an analysis of samples taken in accordance with paragraph (7) demonstrates that there has been no contravention of the prescribed concentration or value in the relevant period, the undertaker may revert to sampling in accordance with paragraph (1).