The Water Intended for Human Consumption (Private Supplies) (Scotland) Regulations 2017

PART C S Indicative dose

Commencement Information

I1 Sch. 4 Pt. C in force at 27.10.2017, see reg. 1(1)

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 that table.

TABLE 3

Minimum performance characteristics: limit of detection

Parameter	Limit of detection (in Bq/l) (Notes 1 and 2)	Notes
Tritium	10	Note 3
Radon	10	Note 3
gross alpha activity	0.04	Note 4
gross beta activity	0.4	Note 4
U-238	0.02
U-234	0.02
Ra-226	0.04
Ra-228	0.02	Note 5
Pb-210	0.02
Po-210	0.01
C-14	20
Sr-90	0.4
Pu-239 / Pu-240	0.04
Am-241	0.06
Co-60	0.5
Cs-134	0.5
Cs-137	0.5
I-131	0.5

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 parametric 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)

This standard has been approved by the International Organization for Standardization (ISO). Under reference BS ISO 11929:2010, it is published as a UK standard by the British Standards Institution (ISBN 978 0 580 59044 3).

(2)

This standard has been approved by the International Organization for Standardization (ISO). Under reference ISO/IEC Guide 98-3:2008 Ed 1, it is published as a UK standard by the British Standards Institution.