18.—(1) An enforcing authority must ensure that regular monitoring of the quality of water in its area is carried out to check that water available to consumers meets the water quality standards.
(2) Where the enforcing authority has reason to suspect that the water contains a micro-organism, parasite or substance (in number or concentration) which—
(a)poses a potential danger to human health; and
(b)is not one of the parameters in Table A, Table B or Table C,
the enforcing authority must ensure that monitoring is carried out to establish whether, at the point of compliance, the micro-organism, parasite or substance poses such a potential danger.
(3) Where disinfection forms part of the preparation or distribution of the water, the enforcing authority must take all measures necessary to ensure that—
(a)the efficiency of the disinfection treatment applied is verified; and
(b)any contamination from disinfection by-products is kept as low as possible without compromising the disinfection.
(4) The enforcing authority must ensure that the monitoring is carried out so as to ensure that the measured values are representative of the quality of the water consumed throughout the year.