# The Private Water Supplies (Wales) Regulations 2017, Part 2: Analytical methods

Extent: E+W

Table 1
Prescribed methods of analysis for microbiological parameters
Parameter
Method
Escherichia coli (E. coli)
EN ISO 9308-1 or EN ISO 9308-2
Enterococci
EN ISO 7899-2
Pseudomonas aeruginosa
EN-ISO 16266
Colony count 22°C — enumeration of culturable microorganisms
EN ISO 6222
Colony count 36°C — enumeration of culturable microorganisms
EN ISO 6222
Clostridium perfringens (including spores)
EN ISO 14189
Table 2
Prescribed performance characteristics for methods of analysis for chemical and indicator parameters: trueness, precision and limit of detection (on or before 31 December 2019)
Parameter
Trueness % of prescribed
concentration or value or specification
(except for pH)
Precision % of prescribed
concentration or value or specification
(except for pH)
Limit of detection %
of prescribed
concentration or
value or specification
(except for pH)
(1)The method of analysis should determine total cyanide in all forms.
(2)EN ISO 8476.
(3)The performance characteristics apply to each individual pesticide and will depend on the pesticide concerned. Values for the uncertainty of measurement as low as 30% can be achieved for several pesticides, higher values up to 80% may be allowed for a number of pesticides.
(4)The performance characteristics apply to the individual substances specified at 25% of the parametric value in Table B of Part 1 of Schedule 1.
(5)The performance characteristics apply to the individual substances specified at 50% of the parametric value in Table B of Part 1of Schedule 1.
(6)The performance characteristics apply to the prescribed value of 4 NTU.
(7)The performance characteristics apply to the specification of 1 NTU for surface waters or ground waters influenced by surface water.
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
10
10
10
1.2-dichloroethane
25
25
10
Fluoride
10
10
10
Hydrogen ion concentration pH (expressed in pH units)
0.2
0.2
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
Oxidisability
Pesticides and related products
25
25
25
Polycyclic aromatic hydrocarbons
25
25
25
Selenium
10
10
10
Sodium
10
10
10
Sulphate
10
10
10
Tetrachloroethene
25
25
10
Tetrachloromethane
20
20
20
Trichloroethene
25
25
10
Trihalomethanes:
Total
25
25
10
Turbidity
10
10
10
Turbidity
25
25
25
Table 3
Method of analysis for chemical and indicator parameters: uncertainty of measurement
Parameter
Uncertainty of measurement
% of parametric value
(except for pH)
(1)The uncertainty of measurement must not be used as an additional tolerance to the parametric values set out in Schedule 1.
(2)If the value of uncertainty of measurement cannot be met, the best available technique should be selected (up to 60%).
(3)The method of analysis should determine total cyanide in all forms.
(4)EN ISO 8476.
(5)The performance characteristics apply to each individual pesticide and will depend on the pesticide concerned. Values for the uncertainty of measurement as low as 30% can be achieved for several pesticides, higher values up to 80% may be allowed for a number of pesticides.
(6)The performance characteristics apply to the individual substances specified at 25% of the parametric value in Table B of Part 1 of Schedule 1.
(7)The performance characteristics apply to the individual substances specified at 50% of the parametric value in Table B of Part 1 of Schedule 1.
(8)The uncertainty of measurement must be estimated at the level of 3mg/l of TOC. CEN 1484 Guidelines for the determination of TOC and dissolved organic carbon must be used.
(9)The uncertainty of measurement must be estimated at the level of 1,0 NTU in accordance with EN ISO 7027.
Aluminium
25
Ammonium
40
Antimony
40
Arsenic
30
Benzene
40
Benzo(a)pyrene
50
Boron
25
Bromate
40
Cadmium
25
Chloride
15
Chromium
30
Conductivity
20
Copper
25
Cyanide
30
1,2-dichloroethane
40
Fluoride
20
Hydrogen ion concentration pH (expressed in pH units)
0.2
Iron
30
Lead
25
Manganese
30
Mercury
30
Nickel
25
Nitrate
15
Nitrite
20
Oxiedisability
50
Pesticides
30
Polycyclic aromatic hydrocarbons
50
Selenium
40
Sodium
15
Sulphate
15
Tetrachloroethene
30
Trichloroethene
40
Trihalomethanes: total
40
Total organic carbon (TOC)
30
Turbidity
30

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Source: https://www.legislation.gov.uk/wsi/2017/1041/schedule/4/part/2 (the official version)
Page: https://openlegislation.uk/private-water-supplies-wales-regulations-2017/schedule-4/part-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.