The Public Water Supplies (Scotland) Amendment Regulations 2022

Regulation 18(4)(c)

SCHEDULE 3 SUBSTITUTION OF TABLE 1 IN SCHEDULE 3 OF THE 2014 REGULATIONS

“Minimum performance characteristic: uncertainty of measurement

Parameter	Uncertainty of measurement (% of prescribed concentration or value, except pH) (Note 1)	Notes
Notes—
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 parametric value stated in the table or any stricter value. The uncertainty of measurement must be estimated at the level of the parametric value, unless otherwise specified.
Note 2: If the value of uncertainty of measurement cannot be met, the best available technique must be selected (up to 60%).
Note 3: The method determines total cyanide in all forms.
Note 4: The value for the uncertainty of measurement is expressed in pH units.
Note 5: Reference method European standard EN ISO 8467:1995 entitled “Water quality - Determination of permanganate index (ISO 8467:1993)”(1).
Note 6: 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 7: The performance characteristics apply to individual substances, specified at 25% of the prescribed concentration or value for the corresponding parameter in Table B.
Note 8: The performance characteristics apply to individual substances, specified at 50% of the prescribed concentration or value for the corresponding parameter in Table B.
Note 9: The uncertainty of measurement must 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”(2).
Note 10: 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)”(3) or another equivalent standard method.”
Aluminium	25
Ammonium	40
Acrylamide	30
Antimony	40
Arsenic	30
Benzo(a)pyrene	50	Note 2
Benzene	40
Bisphenol A	50
Boron	25
Bromate	40
Cadmium	25
Chloride	15
Chlorate	40
Chlorite	40
Chromium	30
Conductivity	20
Copper	25
Cyanide	30	Note 3
1,2-dichloroethane	40
Epichlorohydrin	30
Fluoride	20
HAAs	50
Hydrogen ion concentration (in pH)	0.20	Note 4
Iron	30
Lead	30
Manganese	30
Mercury	30
Microcystin-LR	30
Nickel	25
Nitrate	15
Nitrite	20
Oxidisability	50	Note 5
Pesticides	30	Note 6
PFAS	50
Polycyclic aromatic hydrocarbons	40	Note 7
Selenium	40
Sodium	15
Sulphate	15
Tetrachloroethene	40	Note 8
Trichloroethene	40	Note 8
Trihalomethanes – total	40	Note 7
Total organic carbon	30	Note 9
Turbidity	30	Note 10
Uranium	30
Vinyl chloride	50

(1)

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).

(2)

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.

(3)

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).