Numbers of samples: Type A suppliesS
23.—(1) Subject to paragraph (2) and regulations 21 and 22, in each year a monitoring local authority shall take, or cause to be taken the standard number of samples of water as regards residual disinfectant and each parameter listed in column (2) of Tables A and B in Schedule 2, and shall analyse the samples for compliance with the prescribed concentrations or values or states given in Schedule 1 for those parameters.
(2) Subject to paragraphs (4) and (5), where in respect of a parameter subject to check monitoring—
(a)a monitoring local authority is of the opinion that the quality of water provided by a Type A supply is unlikely to deteriorate;
(b)in each of two successive years the requirement mentioned in paragraph (3) is satisfied in relation to a parameter listed in Table A in Schedule 2; and
(c)the monitoring local authority considers the concentration or value in respect of that parameter is unlikely to increase or, in the case of hydrogen ion (item 9 in Table A in Schedule 2), decrease to any significant extent in the following year,
the number of samples to be taken in that year in respect of that parameter may be the reduced number.
(3) The requirement referred to in paragraph (2)(b) is that an analysis of each sample taken in relation to the parameter in question has shown no significant variation and has established—
(a)if the parameter is colony counts, no abnormal change;
(b)if the parameter in question is hydrogen ion, a pH value that is not less than 6.5 and not more than 9.5; and
(c)in any other case, a concentration or value or state given in Schedule 1 that is constant and significantly better than the prescribed concentration or value or state for that parameter.
(4) Paragraph (2)(b) shall apply in the period from 3rd July 2006 to 2nd July 2008, so that the reduced number of samples may be taken in that period in relation to a parameter if—
(a)it would have been permissible if these Regulations had been in force throughout the period of at least two years mentioned in that paragraph; or
(b)the monitoring local authority did not sample as frequently as required by paragraph (1) during the period from 3rd July 2004 to 2nd July 2006 (“the relevant period”) before these Regulations came into force but an assessment of the samples actually taken during that period, whether or not for the purpose of the 1992 Regulations, justify the reduction.
(5) Except in a case where the provisions of paragraph (6) apply, in the period from 3rd July 2006 to 31st December 2006 the number of samples taken shall be—
(a)not less than one half of the standard number of samples, which number shall be rounded up, if necessary, to the nearest whole number; or
(b)where paragraph (2) applies, not less than one half of the reduced number of samples, which number shall be rounded up, if necessary, to the nearest whole number.
(6) Where, in the period 3rd July 2006 to 31st December 2006, the number of samples to be taken by virtue of paragraph (5) in relation to a parameter is 1, the monitoring local authority need not sample that parameter if a sample has been taken by that authority in respect of that supply in the period 1st January 2006 to 2nd July 2006, whether or not for the purposes of the 1992 Regulations.
(7) Where the analysis of the reduced number of samples taken by a monitoring local authority has established in respect of any parameter listed in Tables A and B in Schedule 2 that the prescribed specification for that parameter or, as the case may be, the relaxed specification for that parameter or, as the case may be, the relaxed specification therefor specified in an authorisation granted under Part V has been contravened, the monitoring local authority shall revert to carrying out—
(a)the number of samples proportionate to the remainder of that year in respect of that parameter; and where the result is not a whole number, that proportion rounded up to the nearest whole number; and
(b)for subsequent years, the standard number of samples.
(8) Samples required to be taken by this regulation shall be taken so that they are representative of the quality of water intended for human consumption purposes throughout the year.
(9) In this regulation, “the standard number” means, in relation to each parameter listed in column (2) of Tables A and B in Schedule 2, the relevant number shown for each parameter in those Tables in the columns for levels 1 to 3 respectively; and “the reduced number” means, in relation to each parameter listed in column (2) of Table A of that Schedule, the relevant number shown for each parameter in brackets in the columns for those levels.