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The Public Water Supplies (Scotland) Amendment Regulations 2017

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Regulation 10

SCHEDULE 2SUBSTITUTION OF SCHEDULE 3 OF THE 2014 REGULATIONS

This schedule has no associated Policy Notes

Regulation 14A(1) and (2)

SCHEDULE 3METHODS OF ANALYSIS

1.(1) Scottish Water must ensure that the methods of analysis used for the purposes of monitoring and demonstrating compliance with these Regulations are validated and documented in accordance with European standard EN ISO/IEC 17025:2005 entitled “General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:2005)(3), or other equivalent standards accepted at international level.

(2) Scottish Water must ensure that laboratories or parties contracted by laboratories apply quality management system practices in accordance with European standard EN ISO/IEC 17025:2005 entitled “General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:2005)”, or other equivalent standards accepted at international level.

2.  In the absence of an analytical method meeting the minimum performance criteria set out in Part B of this schedule, Scottish Water must ensure that monitoring is carried out using best available techniques not entailing excessive costs.

PART AMicrobiological parameters

1.(1) Subject to sub-paragraph (2), the methods in paragraph 2 are given for reference.

(2) Scottish Water may use other methods, providing the provisions of regulation 14A are met.

2.  The methods for microbiological parameters are—

(a)for Escherichia coli and coliform bacteria—

(i)European standard EN ISO 9308-1:2014 entitled “Water quality - Enumeration of Escherichia coli and coliform bacteria - Part 1: Membrane filtration method for waters with low bacterial background flora (ISO 9308-1:2014)(4); or

(ii)European standard EN ISO 9308-2:2014 entitled “Water quality - Enumeration of Escherichia coli and coliform bacteria - Part 2: Most probable number method (ISO 9308-2:2012)(5);

(b)for enterococci, European standard EN ISO 7899-2:2000 entitled “Water quality - Detection and enumeration of intestinal enterococci - Part 2: Membrane filtration method (ISO 7899-2:2000)(6);

(c)for Pseudomonas aeruginosa, European standard EN ISO 16266:2008 entitled “Water quality - Detection and enumeration of Pseudomonas aeruginosa - Method by membrane filtration (ISO 16266:2006)(7);

(d)for colony count 22 °C (the enumeration of culturable microorganisms — colony count after aerobic incubation at 22 °C), European standard EN ISO 6222:1999 entitled “Water quality - Enumeration of culturable micro-organisms - Colony count by inoculation in a nutrient agar culture medium (ISO 6222:1999)(8);

(e)for colony count 36 °C (the enumeration of culturable microorganisms — colony count after aerobic incubation at 36 °C), European standard EN ISO 6222:1999 entitled “Water quality - Enumeration of culturable micro-organisms - Colony count by inoculation in a nutrient agar culture medium (ISO 6222:1999)”; and

(f)for Clostridium perfringens including spores, European standard EN ISO 14189:2016 entitled “Water quality - Enumeration of Clostridium perfringens - Method using membrane filtration (ISO 14189:2013)(9).

PART BChemical and indicator parameters

1.(1) Subject to paragraph 3, for a parameter in Table 1, the method of analysis used must, as a minimum, be capable of measuring concentrations equal to the prescribed concentration or value for the parameter with—

(a)a limit of quantification of 30 % or less of the prescribed concentration or value for the parameter; and

(b)an uncertainty of measurement as specified in Table 1 for the parameter.

(2) The result of the analysis for a parameter in Table B or Table C must be expressed using at least the same number of significant figures as the prescribed concentration or value for the parameter in the table.

2.  The uncertainty of measurement specified in Table 1 for a parameter must not be used as an additional tolerance to the prescribed concentration or value for the parameter.

3.  Until 31st December 2019, Scottish Water may, for a parameter in Table 2, use the corresponding ‘trueness’, ‘precision’ and ‘limit of detection’ in that table as an alternative set of performance characteristics (instead of using the limit of quantification and the uncertainty of measurement referred to in paragraph 1(1)).

TABLE 1
Minimum performance characteristic: uncertainty of measurement
ParameterUncertainty of measurement (% of prescribed concentration or value, except pH) (Note 1)Notes(10)
Aluminium25
Ammonium40
Antimony40
Arsenic30
Benzo(a)pyrene50Note 5
Benzene40
Boron25
Bromate40
Cadmium25
Chloride15
Chromium30
Conductivity20
Copper25
Cyanide30Note 6
1,2-dichloroethane40
Fluoride20
Hydrogen ion concentration (in pH)0.2Note 7
Iron30
Lead25
Manganese30
Mercury30
Nickel25
Nitrate15
Nitrite20
Oxidisability50Note 8
Pesticides30Note 9
Polycyclic aromatic hydrocarbons30Note 10
Selenium40
Sodium15
Sulphate15
Tetrachloroethene30Note 11
Trichloroethene40Note 11
Trihalomethanes: total40Note 10
Total organic carbon30Note 12
Turbidity30Note 13
TABLE 2
Minimum performance characteristics: trueness, precision and limit of detection
ParameterTrueness (% of prescribed concentration or value, except for pH) (Note 2)Precision (% of prescribed concentration or value, except for pH) (Note 3)Limit of detection (% of prescribed concentration or value, except for pH) (Note 4)Notes(11)
Aluminium101010
Ammonium101010
Antimony252525
Arsenic101010
Benzo(a)pyrene252525
Benzene252525
Boron101010
Bromate252525
Cadmium101010
Chloride101010
Chromium101010
Conductivity101010
Copper101010
Cyanide101010Note 6
1,2-dichloroethane252510
Fluoride101010
Hydrogen ion concentration (in pH)0.20.2Note 7
Iron101010
Lead101010
Manganese101010
Mercury201020
Nickel101010
Nitrate101010
Nitrite101010
Oxidisability252525Note 8
Pesticides252525Note 9
Polycyclic aromatic hydrocarbons252525Note 10
Selenium101010
Sodium101010
Sulphate101010
Tetrachloroethene252510Note 11
Trichloroethene252510Note 11
Trihalomethanes: total252510Note 10
Turbidity252525
Notes to Table 1 and Table 2
Note 1: 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 prescribed concentration or value for the parameter stated in the table or better. Measurement uncertainty must be estimated at the level of the prescribed concentration or value for the parameter, unless otherwise specified.
Note 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 international standard ISO 5725 entitled “Accuracy (trueness and precision) of measurement methods and results”(12).
Note 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 international standard ISO 5725 entitled “Accuracy (trueness and precision) of measurement methods and results”.
Note 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).
Note 5: If the value of uncertainty of measurement cannot be met, the best available technique should be selected (up to 60 %).
Note 6: The method determines total cyanide in all forms.
Note 7: Values for trueness, precision and uncertainty of measurement are expressed in pH units.
Note 8: Reference method European standard EN ISO 8467:1995 entitled “Water quality - Determination of permanganate index (ISO 8467:1993)”(13).
Note 9: 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.
Note 10: The performance characteristics apply to individual substances, specified at 25 % of the prescribed concentration or value for the corresponding parameter in Table B.
Note 11: The performance characteristics apply to individual substances, specified at 50 % of the prescribed concentration or value for the corresponding parameter in Table B.
Note 12: The uncertainty of measurement should be estimated at the level of 3 mg/l of the total organic carbon in accordance with European standard EN 1484:1997 entitled “Water analysis - Guidelines for the determination of total organic carbon and dissolved organic carbon”(14).
Note 13: The uncertainty of measurement must be estimated at the level of 1.0 nephelometric turbidity units in accordance with European standard EN ISO 7027-1:2016 entitled “Water quality - Determination of turbidity - Part 1: Quantitative methods (ISO 7027-1:2016)”(15).

PART CIndicative dose

For each parameter in Table 3, the method of analysis used must be capable of measuring activity concentrations with at least the limit of detection specified for that parameter in the second column of the table.

TABLE 3
Minimum performance characteristics: limit of detection
ParameterLimit of detection (in Bq/l) (Notes 1 and 2)Notes
Tritium10Note 3
Radon10Note 3
gross alpha activity0.04Note 4
gross beta activity0.4Note 4
U-2380.02
U-2340.02
Ra-2260.04
Ra-2280.02Note 5
Pb-2100.02
Po-2100.01
C-1420
Sr-900.4
Pu-239 / Pu-2400.04
Am-2410.06
Co-600.5
Cs-1340.5
Cs-1370.5
I-1310.5
Notes to Table 3
Note 1: The limit of detection must be calculated in accordance with the international standard ISO 11929:2010 entitled “Determination of the characteristic limits (decision threshold, detection limit and limits of the confidence interval) for measurements of ionising radiation - Fundamentals and application”(1), with probabilities of errors of 1st and 2nd kind of 0.05 each.
Note 2: Measurement uncertainties must be calculated and reported as complete standard uncertainties, or as expanded standard uncertainties with an expansion factor of 1.96, in accordance with international standard ISO/IEC Guide 98-3:2008 entitled “Guide to the expression of uncertainty in measurement”(2).
Note 3: The limit of detection for tritium and for radon is 10% of the corresponding prescribed concentration or value for the parameter.
Note 4: The limit of detection for gross alpha activity and gross beta activities is 40% of the screening values of 0.1 Bq/l and 1.0 Bq/l respectively.
Note 5: This limit of detection applies only to initial screening for indicative dose for a new water source. If initial checking indicates that it is unlikely that Ra-228 exceeds 20% of the derived concentration, the limit of detection may be increased to 0.08 Bq/l for routine Ra-228 nuclide specific measurements, until a subsequent re-check is required.
(1)

1972 c.68. Section 2(2) was amended by the Scotland Act 1998 (c.46) (“the 1998 Act”), schedule 8, paragraph 15(3) (which was amended by section 27(4) of the Legislative and Regulatory Reform Act 2006 (c.51) (“the 2006 Act”)). Section 2(2) was also amended by section 27(1)(a) of the 2006 Act and by the European Union (Amendment) Act 2008 (c.7) (“the 2008 Act”), schedule, Part 1. Paragraph 1A of schedule 2 was inserted by the 2006 Act, section 28 and amended by the 2008 Act, schedule, Part 1. The functions conferred on a Minister of the Crown under section 2(2) of the European Communities Act 1972 are, so far as they are exercisable within devolved competence, exercisable by the Scottish Ministers by virtue of section 53 of the 1998 Act. Section 2(2) is cited so far as is necessary (to supplement the other powers cited) for the purposes of implementing, or enabling the implementation of, obligations arising under or by virtue of Directive 98/83/EC and Directive 2013/51/EURATOM. In particular, section 2(2) is cited so far as is necessary to enable the making of the provision in regulation 4(7) which confers a power of direction on the Drinking Water Regulator for Scotland.

(3)

This standard was approved by the European Committee for Standardization (CEN) on 15th March 2005. Under reference BS EN ISO/IEC 17025:2005, it is published as a UK standard by the British Standards Institution (ISBN 0 580 46330 3).

(4)

This standard was approved by the European Committee for Standardization (CEN) on 18th January 2017. Under reference BS EN ISO 9308-1:2014+A1:2017, it is published as a UK standard by the British Standards Institution (ISBN 978 0 580 92379 1).

(5)

This standard was approved by the European Committee for Standardization (CEN) on 11th April 2014. Under reference BS EN ISO 9308-2:2014, it is published as a UK standard by the British Standards Institution (ISBN 978 0 580 84023 4).

(6)

This standard was approved by the European Committee for Standardization (CEN) on 11th April 2014. Under reference BS EN ISO 7899-2:2000, it is published as a UK standard by the British Standards Institution (ISBN 0 580 34953 5).

(7)

This standard was approved by the European Committee for Standardization (CEN) on 11th January 2008. Under reference BS EN ISO 16266:2008, it is published as a UK standard by the British Standards Institution (ISBN 978 0 580 59736 7).

(8)

This standard was approved by the European Committee for Standardization (CEN) on 16th March 1999. Under reference BS EN ISO 6222:1999, it is published as a UK standard by the British Standards Institution (ISBN 0 580 32495 8).

(9)

This standard was approved by the European Committee for Standardization (CEN) on 15th July 2016. Under reference BS EN ISO 14189:2016, it is published as a UK standard by the British Standards Institution (ISBN 978 0 580 92184 1).

(10)

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

(11)

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

(12)

This standard has been approved by the International Organization for Standardization (ISO). Under reference BS ISO 5725-1 to BS ISO 5725-6, these are published as UK standards by the British Standards Institution.

(13)

This standard was approved by the European Committee for Standardization (CEN) on 3rd November 1994. Under reference EN ISO 8467:1995, it is published as a UK standard by the British Standards Institution (ISBN 0 580 23435 5).

(14)

This standard was approved by the European Committee for Standardization (CEN) on 6th April 1997. Under reference BS EN 1484:1997, it is published as a UK standard by the British Standards Institution (ISBN 0 580 28372 0).

(15)

This standard was approved by the European Committee for Standardization (CEN) on 15th April 2016. Under reference BS EN ISO 7027-1:2016, it is published as a UK standard by the British Standards Institution (ISBN 978 0 580 81961 2).

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