The Private Water Supplies Regulations (Northern Ireland) 2009

Regulation 12

SCHEDULE 4 Sampling and Analysis

PART 1 General

Samples: general

1.—(1) The Department shall ensure that each sample taken in accordance with a monitoring programme is—

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

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

(c) kept at such temperature and in such conditions as will secure that there is no material alteration of a concentration, value or state of any parameter for which the sample is to be analysed; and

(d) analysed as soon as may be after it has been taken—

(i) by a person who is competent to perform that task; and

(ii) with the use of such equipment as is suitable for the purpose.

Analysing samples

2.—(1) The Department shall ensure that each sample is analysed in accordance with this paragraph.

(2) For each parameter specified in the first column of Table A in Part 2 of this Schedule—

(a) the method of analysis specified in the second column of that table; or

(b) an alternative method of analysis authorised under paragraph 3;

(3) For each parameter specified in the first column of Table B in Part 2 of this Schedule the method of analysis 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, a method of analysis which is capable at the time of use of measuring a value with a trueness of 0.2 pH unit and a precision of 0.2 pH unit.

(5) For these purposes—

“limit of detection” is to be calculated as—

(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 to be calculated as twice the standard deviation (within a batch and between batches) of the spread of results about the mean; and

“trueness” (the systematic error) is to be calculated as 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) If the Department is satisfied that an alternative method of analysis is at least as reliable as a method of analysis prescribed by paragraph 2(2)(a), it may authorise its use instead of the prescribed method.

(2) The Department shall provide the European Commission with relevant information concerning such methods and their equivalence.

Laboratories

4.  The Department shall ensure that any laboratory at which samples are analysed has a system of analytical quality control that is subjected from time to time to checking by a person who is—

(a) not under the control of either the laboratory or the Department; and

(b) approved by the Department for that purpose.

Interpretation

5.  In this schedule—

“laboratory” includes any land at which samples are analysed for the purposes of these Regulations (including on-site analysis); and

“taking and analysing samples” includes taking, handling, transporting, storing and analysing samples.

PART 2 Analytical Methods

TABLE A

Prescribed methods of analysis

(1) Parameter	(2) Method
*Use the following method to make m-CP agar:
Make a basal medium consisting of—
30.0g Tryptose;
20.0g Yeast extract;
5.0g Sucrose;
1.0g L-cysteine hydrochloride;
0.1g MgSO4.7 H2O;
40.0mg Bromocresol purple;
15.0g Agar; and
1,000.0ml Water.
Dissolve the ingredients of the basal medium, adjust pH to 7.6 and autoclave at 121°C for 15 minutes. Allow the medium to cool. Dissolve the following into 8ml sterile water before adding to the medium—
400.0mg D-cycloserine;
25.0mg Polymyxine-B sulphate; and
60.0mg Indoxyl-β-D-glucoside.
Add to the medium—
20.0 ml Filter-sterilised 0.5% phenolphthalein diphosphate solution; and
2.0ml Filter-sterilised 4.5% FeCl3.6H2O
Clostridium perfringens (including spores)	Membrane filtration followed by anaerobic incubation of the membrane on m-CP agar* at 44 ± 1°C for 21 ± 3 hours. Count opaque yellow colonies that turn pink or red after exposure to ammonium hydroxide vapours for 20 to 30 seconds.
Coliform bacteria	BS-EN ISO 9308-1
Colony count 22°C-enumeration of culturable microorganisms	BS-EN ISO 6222
Colony count 37°C-enumeration of culturable microorganisms	BS-EN ISO 6222
Enterococci	BS-EN ISO 7899-2
Escherichia coli (E. coli)	BS-EN ISO 9308-1

TABLE B

Prescribed performance characteristics for methods of analysis

(1) The method of analysis should determine total cyanide in all forms.
(2) The performance characteristics apply to each individual pesticide and will depend on the pesticide concerned.
(3) The performance characteristics apply to the individual substances specified at 25% of the parametric value in Table B of Part 1 of Schedule 1.
(4) The performance characteristics apply to the individual substances specified at 50% of the parametric value in Table B of Part 1 of Schedule 1.
(5) The performance characteristics apply to the prescribed value of 4 NTU.
(6) The performance characteristics apply to the specification of 1 NTU for water leaving surface water treatment works.
(1) Parameters	(2) Trueness % of prescribed concentration or value or specification	(3) Precision % of prescribed concentration or value or specification	(4) Limit of detection % of prescribed concentration or value or specification
Aluminium	10	10	10
Ammonium	10	10	10
Antimony	25	25	25
Arsenic	10	10	10
Benzene	25	25	25
Benzo(a)pyrene	25	25	25
Boron	10	10	10
Bromate	25	25	25
Cadmium	10	10	10
Chloride	10	10	10
Chromium	10	10	10
Colour	10	10	10
Conductivity	10	10	10
Copper	10	10	10
Cyanide (1)	10	10	10
1,2-dichloroethane	25	25	10
Fluoride	10	10	10
Iron	10	10	10
Lead	10	10	10
Manganese	10	10	10
Mercury	20	10	20
Nickel	10	10	10
Nitrate	10	10	10
Nitrite	10	10	10
Pesticides and related products (2)	25	25	25
Polycyclic aromatic hydrocarbons (3)	25	25	25
Selenium	10	10	10
Sodium	10	10	10
Sulphate	10	10	10
Tetrachloroethene (4)	25	25	10
Tetrachloromethane	20	20	20
Trichloroethene (4)	25	25	10
Trihalomethanes: Total (3)	25	25	10
Turbidity(5)	10	10	10
Turbidity(6)	25	25	25