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The Private Water Supplies Regulations (Northern Ireland) 2017

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PART 2Analytical Methods and Performance Characteristics

TABLE A

Prescribed methods of analysis

(1) Parameter(2) Method
Clostridium perfringens (including spores)EN ISO 14189
Coliform bacteriaEN ISO 9308-1 or EN ISO 9308-2
Colony count 22°C-enumeration of culturable microorganismsEN ISO 6222
EnterococciEN ISO 7899-2
Escherichia coli (E. coli)EN ISO 9308-1 or EN ISO 9308-2
Pseudomonas aeruginosaEN ISO 16266

TABLE B

Minimum performance characteristic: “uncertainty of measurement”

(1) Parameter(1)(2) Uncertainty of measurement (% of parametric value, except pH)(2)
(1)

Acrylamide, epichlorohydrin and vinyl chloride to be controlled by product specification.

(2)

Uncertainty of measurement is a non-negative parameter characterising the dispersion of the quantity values being attributed to a measurand, based on the information used. The performance criterion for measurement uncertainty (k = 2) is the percentage of the parametric value stated in the table or better. Measurement uncertainty must be estimated at the level of the parametric value, unless otherwise specified.

(3)

If the value of uncertainty of measurement cannot be met, the best available technique should be selected (up to 60%).

(4)

The method determines total cyanide in all forms.

(5)

Values for trueness, precision and uncertainty of measurement are expressed in pH units.

(6)

Reference method EN ISO 8467.

(7)

The performance characteristics for individual pesticides are given as an indication. 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.

(8)

The performance characteristics apply to individual substances, specified at 25% of the parametric value in Table B of Schedule 1.

(9)

The performance characteristics apply to individual substances, specified at 50% of the parametric value in Table B of Schedule 1.

(10)

The uncertainty of measurement should be estimated at the level of 3 mg/l of the total organic carbon. CEN 1484 Guidelines for the determination of total organic carbon and dissolved organic carbon must be used.

(11)

The uncertainty of measurement must be estimated at the level of 1.0 NTU (nephelometric turbidity units) in accordance with EN ISO 7027.

Aluminium25
Ammonium40
Antimony40
Arsenic30
Benzo(a)pyrene(3)50
Benzene40
Boron25
Bromate40
Cadmium25
Chloride15
Chromium30
Colour20
Conductivity20
Copper25
Cyanide(4)30
1,2-dichloroethane40
Fluoride20
Hydrogen ion concentration pH (expressed in pH units)(5)0.2
Iron30
Lead25
Manganese30
Mercury30
Nickel25
Nitrate15
Nitrite20
Oxidisability(6)50
Pesticides(7)30
Polycyclic aromatic hydrocarbons(8)50
Selenium40
Sodium15
Sulphate15
Tetrachloroethene(9)30
Tetrachloromethane30
Trichloroethene(9)40
Trihalomethanes: total(8)40
Total organic carbon(10)30
Turbidity(11)30

TABLE C

Minimum performance characteristics: trueness, precision and limit of detection- may be used until 31 December 2019

(1) Parameter(1)

(2) Trueness

(% of parametric value, except for pH)(2)

(3) Precision

(% of parametric value, except for pH)(3)

(4) Limit of detection

(% of parametric value, except for pH)(4)

(1)

Acrylamide, epichlorohydrin and vinyl chloride to be controlled by product specification.

(2)

Trueness is a measure of systematic error, i.e. the difference between the mean value of the large number of repeated measurements and the true value. Further specifications are those set out in ISO 5725.

(3)

Precision is a measure of random error and is usually expressed as the standard deviation (within and between batches) of the spread of results from the mean. Acceptable precision is twice the relative standard deviation. This term is further specified in ISO 5725.

(4)

Limit of detection is either three times the standard deviation within a batch of a natural sample containing a low concentration of the parameter; or five times the standard deviation of a blank sample (within a batch).

(5)

The method determines total cyanide in all forms.

(6)

Values for trueness, precision and uncertainty of measurement are expressed in pH units.

(7)

Reference method EN ISO 8467.

(8)

The performance characteristics for individual pesticides are given as an indication. 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.

(9)

The performance characteristics apply to individual substances, specified at 25% of the parametric value in Table B of Schedule 1.

(10)

The performance characteristics apply to individual substances, specified at 50% of the parametric value in Table B of Schedule 1.

(11)

The performance characteristics apply to prescribed value 4 NTU.

(12)

The performance characteristics apply to prescribed value 1 NTU for water leaving surface water treatment works.

Aluminium101010
Ammonium101010
Antimony252525
Arsenic101010
Benzene252525
Benzo(a)pyrene252525
Boron101010
Bromate252525
Cadmium101010
Chloride101010
Chromium101010
Colour101010
Conductivity101010
Copper101010
Cyanide(5)101010
1,2-dichloroethane252510
Fluoride101010
Hydrogen ion concentration pH (expressed in pH units)(6)0.20.2
Iron101010
Lead101010
Manganese101010
Mercury201020
Nickel101010
Nitrate101010
Nitrite101010
Oxidisability(7)502510
Pesticides(8)252525
Polycyclic aromatic hydrocarbons(9)252525
Selenium101010
Sodium101010
Sulphate101010
Tetrachloroethene(10)252510
Tetrachloromethane202020
Trichloroethene(10)252510
Trihalomethanes: total(9)252510
Turbidity(11)101010
Turbidity(12)252525

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