The Private Water Supplies (Wales) Regulations 2010

PART 1 General

Samples: general

1.—(1) The local authority must ensure that each sample is—

(d) taken by a competent person using suitable equipment;

(e) representative of the water at the sampling point at the time of sampling;

(f) not contaminated in the course of being taken;

(g) kept at such temperature and in such conditions as will secure that there is no material change in what is to be measured; and

(h) analysed without delay by a competent person using suitable equipment.

(2) It must ensure that the sample is analysed using a system of analytical quality control.

(3) The system must be subjected to checking by a person who is—

(a) not under the control of either the analyst or the local authority; and

(b) approved by the Welsh Ministers for that purpose.

Analysing samples

2.—(1) The local authority must ensure that each sample is analysed in accordance with this paragraph.

(2) For each parameter specified in the first column of Table 1 in Part 2 of this Schedule the method of analysis is specified in the second column of that table.

(3) For each parameter specified in the first column of Table 2 in Part 2 of this Schedule the method is one that is capable of—

(a) measuring concentrations and values with the trueness and precision specified in the second and third columns of that table, and

(b) detecting the parameter at the limit of detection specified in the fourth column of that table.

(4) For hydrogen ion, the method of analysis must be capable of measuring a value with a trueness of 0.2 pH unit and a precision of 0.2 pH unit.

(5) The method of analysis used for odour and taste parameters must be capable of measuring values equal to the parametric value with a precision of 1 dilution number at 25°C.

(5) For these purposes—

• “limit of detection” is —

  (a)

  three times the relative within-batch standard deviation of a natural sample containing a low concentration of the parameter; or

  (b)

  five times the relative within-batch standard deviation of a blank sample;

• “precision” (the random error) is twice the standard deviation (within a batch and between batches) of the spread of results about the mean;

• “trueness” (the systematic error) is the difference between the mean value of the large number of repeated measurements and the true value.

Authorisation of alternative methods of analysis

3.—(1) The Welsh Ministers may authorise a method different from that set out in paragraph 2(2) if satisfied that it is at least as reliable.

(2) An authorisation may be time-limited and may be revoked at any time.

Sampling and analysis by persons other than local authorities

4.—(1) A local authority may enter into an arrangement for any person to take and analyse samples on its behalf.

(2) A local authority must not enter into an arrangement under paragraph (1) unless—

(a) it is satisfied that the task will be carried out promptly by a person competent to perform it, and

(b) it has made arrangements that ensure that any breach of these Regulations is communicated to it immediately, and any other result is communicated to it within 28 days.