The Water Supply (Water Quality) Regulations 1989

Wholesomeness

3.—(1) This regulation has effect subject to Part III of these Regulations.

(2) Subject to paragraph (7), water supplied to any premises for such domestic purposes as consist in or include drinking, washing or cooking shall be regarded as wholesome for the purposes of Chapter II, as it applies to the supply of water for those domestic purposes, if the requirements of paragraph (3) below are satisfied; and, where the water has been softened or desalinated and is to be supplied for drinking or cooking, the requirements of paragraph (4) are also satisfied.

(3) The requirements of this paragraph are–

(a) that the water does not contain any element, organism or substance (other than a parameter) at a concentration or value which would be detrimental to public health;

(b) that the water does not contain any element, organism or substance (whether or not a parameter) at a concentration or value which in conjunction with any other element, organism or substance it contains (whether or not a parameter) would be detrimental to public health;

(c) subject to paragraphs (5) and (6) below, that the water does not contain concentrations or values of the parameters listed in Tables A to C in excess of the prescribed concentrations or values;

(d) that samples taken in respect of the parameters listed in Table D from water supplied to the water supply zone in question have established that the average concentrations or values of those parameters over the preceding 12 months did not exceed those specified in that Table; and

(e) that samples taken from water supplied to the water supply zone in question have established that the average concentrations over the three preceding months of trihalomethanes (being the aggregate of the concentrations of trichloromethane, dichlorobromomethane, dibromochloromethane and tribromomethane) did not exceed 100 μg/1, or where (by virtue of regulation 13(3)) less than four samples are taken in any year, no sample contained a concentration of trihalomethanes in excess of 100 μg/1.

(4) The requirements of this paragraph are that the water’s hardness or its alkalinity is not below the relevant minimum specified in Table E.

(5) Water shall not be regarded as unwholesome by virtue of paragraph (2)(c) above solely by reason of a sodium concentration exceeding that specified in relation to item 9 in Table A (sodium) if 80% of the results of analysis of all the samples taken in accordance with these Regulations within the preceding 36 months from sampling points within the water supply zone in question demonstrate a concentration of sodium within the relevant maximum specified in that Table.

(6) Water shall not be regarded as unwholesome by virtue of paragraph (2)(c) above solely by reason of the presence in it of total coliforms (item 1 of Table C) if 95% of the results of analysis of–

(a) every sample taken in the preceding year in respect of that parameter in accordance with these Regulations; or

(b) if less than 50 samples have been so taken, the last 50 samples taken in respect of that parameter in accordance with these Regulations,

establish the absence of such coliforms.

(7) Water supplied to any premises for such domestic purposes as are mentioned in paragraph (2) shall be regarded as unwholesome for the purposes of Chapter II if on transfer from a treatment works or service reservoir for supply for such domestic purposes it contained a concentration of any of the parameters listed in Table C in excess of the prescribed concentration.