# The Private Water Supplies Regulations (Northern Ireland) 2017, Paragraph 8: Performance characteristics and method of analysis.


For the following parameters and radionuclides, the method of analysis used must, as a minimum be capable of measuring activity concentrations with a limit of detection specified below in Table E:
TABLE E
1 The limit of detection must be calculated according to the ISO standard 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”, with probabilities of errors of 1st and 2nd kind of 0.05 each.
2 Measurement uncertainties must be calculated and reported as complete standard uncertainties, or as expanded standard uncertainties with an expansion factor of 1.96, according to the ISO IEC Guide 98-3:2008 entitled “Guide to the expression of uncertainty in measurement”.
3 The limit of detection for tritium and for radon is 10% of the corresponding parametric value of 100 Bg/l.
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.
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.
Parameters and radiouclides
Limit of detection12
Tritium
10 Bg/l3
Radon
10 Bg/l3
gross alpha activity
0.04 Bg/l4
gross beta activity
0.4 Bg/l4
U-238
0.02 Bg/l
U-234
0.02 Bg/l
Ra-226
0.04 Bg/l
Ra-228
0.02 Bg/l5
Pb-210
0.02 Bg/l
Po-210
0.01 Bg/l
C-14
20 Bg/l
Sr-90
0.4 Bg/l
Pu-239/Pu-240
0.04 Bg/l
Am-241
0.06 Bg/l
Co-60
0.5 Bg/l
Cs-134
0.5 Bg/l
Cs-137
0.5 Bg/l
I-131
0.5 Bg/l

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Source: https://www.legislation.gov.uk/nisr/2017/211/schedule/4/paragraph/8 (the official version)
Page: https://openlegislation.uk/private-water-supplies-regulations-northern-ireland-2017/schedule-4/paragraph-8
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.