# The Water Supply (Water Quality) Regulations (Northern Ireland) 2017, Schedule 2: INDICATOR PARAMETERS


1 May be monitored from samples of water leaving treatment works or other supply point, as no significant change during distribution.
2 The water should not be aggressive.
3 Where radon concentrations exceed 1000Bq/l, remedial action must be carried out on radiological protection grounds without further consideration.
4 Excluding tritium, potassium-40, radon and radon decay products.
5 Elevated levels of tritium may indicate the presence of other artificial radionuclides. If the tritium concentration exceeds its parametric value, an analysis of the presence of other radionuclides is required.
6 Where treatment to reduce the level of radionuclides in water intended for human consumption has been taken, monitoring must be carried out to ensure the continued efficacy of the treatment.
7 If the gross alpha activity exceeds 0.1Bq/l or gross beta activity exceeds 1.0Bq/l, analysis for specific radionuclides is required.
(1) Item
(2) Parameters
(3) Specification Concentration or Value (maximum unless otherwise stated) or State
(4) Units of Measurement
(5) Point of monitoring
1
Ammonium
0.50
mg/l
Consumers' taps
2
Chloride12
250
mg/l
Supply point
3
Clostridium perfringens (including spores)1
0
Number/100ml
Supply point
4
Coliform bacteria
0
Number/100ml
Consumers' taps
5
Colony counts
No abnormal change
Number/1ml at 22°C Number/1ml at 37°C
Consumers' taps, service reservoirs and treatment works
6
Conductivity12
2500
µS/cm at 20°C
Supply point
7
Hydrogen ion2
9.5
pH units
Consumers' taps
6.5 (minimum)
8
Radon (for radioactivity)136
100
Bq/l
Supply point
9
Sulphate12
250
mg/l
Supply point
10
Indicative dose (for radioactivity)1467
0.10
mSv
Supply point
11
Total organic carbon (TOC)1
No abnormal change
mg/l
Supply point
12
Tritium (for radioactivity)156
100
Bq/l
Supply point
13
Turbidity
1
NTU
Treatment works

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Source: https://www.legislation.gov.uk/nisr/2017/212/schedule/2 (the official version)
Page: https://openlegislation.uk/water-supply-water-quality-regulations-northern-ireland-2017/schedule-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.