Sampling at service reservoirs
13.—(1) Every water undertaker or supplementary licensee must take, or cause to be taken, from each of its service reservoirs in each week in which the reservoir is in use or as directed by notification by the Welsh Ministers under regulation 9(4), one sample for analysis—
(a)for testing for compliance with the prescribed concentrations or values in respect of the parameters E coli and coliform bacteria;
(b)for determining the concentration of residual disinfectant; and
(c)for determining whether the specification in relation to the colony counts parameter is met.