SCHEDULE 2
Regulation 7
SCHEDULE 3A

Monitoring of radioactive substances
Regulation 6A

Radon
1
1
In relation to the radon parameter in the radioactive substances parameters table, a water undertaker—
a
must ensure that a representative survey is carried out in accordance with sub-paragraph (2) to determine the likelihood of a supply failing to comply with the relevant parametric concentration or value specified in the radioactive substances parameters table; and
b
must carry out monitoring where there is reason to believe, on the basis of the results of the representative surveys or other reliable information, including any risk assessment carried out in accordance with regulation 28, that the parametric value for the radon parameter laid down in the radioactive substances parameters table might be exceeded.
2
A representative survey must be designed in such a way—
a
as to be capable of determining the scale and nature of likely exposure to radon in water intended for human consumption originating from different types of groundwater sources and wells in different geological areas; and
b
that underlying parameters, especially the geology and hydrology of the area, radioactivity of rock or soil, and well type, can be identified and used to direct further action to areas of likely high exposure.

Tritium
2
1
In relation to the tritium parameter in the radioactive substances parameters table, a water undertaker—
a
must carry out monitoring where an anthropogenic source of tritium or other artificial radionuclides is present within a water supply zone and it cannot be shown on the basis of other surveillance programmes or investigations, including any risk assessment carried out in accordance with regulation 28, that the level of tritium is below the parametric value listed in the radioactive substances parameters table; and
b
must carry out an investigation of the presence of other artificial radionuclides if the concentration of tritium exceeds the parametric value listed in the radioactive substances parameters table.
2
Where monitoring is required by sub-paragraph (1) samples must be taken in accordance with regulation 9(1) and (3).

Indicative Dose
3
1
In relation to the indicative dose (“ID”) parameter in the radioactive substances parameters table, a water undertaker must carry out monitoring where a source of artificial radioactivity or elevated natural radioactivity is present in a water supply zone and it cannot be shown on the basis of other surveillance programmes or investigations, including any risk assessment carried out in accordance with regulation 28, that the level of ID is below the parametric value listed the radioactive substances parameters table.
2
Where monitoring is required by sub-paragraph (1) in relation to artificial radionuclides samples must be taken in accordance with regulation 9(1) and (3).
3
Where monitoring is required by sub-paragraph (1) in relation to a source of elevated natural radioactivity—
a
the Welsh Ministers must specify, by notice in writing to the water undertaker, the frequency of the monitoring required of—
i
gross alpha activity;
ii
gross beta activity; or
iii
individual natural radionuclides,
depending on the screening strategy adopted by the water undertaker pursuant to Schedule 5; and
b
the frequency of monitoring required under sub-paragraph (a) may vary from a single check measurement to the frequencies required for sampling in accordance with regulation 9(1).
4
Where a single check for natural radioactivity is specified under paragraph (3)(a), the water undertaker must carry out a further check if any change occurs in relation to the supply which is likely to influence the concentrations of radionuclides in the supply.

Water treatment
4
Where treatment to reduce the level of radionuclides in a water supply zone has been undertaken, to verify the continued efficacy of that treatment, the water undertaker must—
a
monitor the supply for total indicative dose, radon and tritium in accordance the provisions of this Schedule; and
b
take samples in accordance with regulation 9(1) and (3).

Averaging
5
Where a parametric value in the radioactive substances parameters table is exceeded in relation to a particular sample taken by a water undertaker, the Welsh Ministers must specify, by notice in writing to the water undertaker, the extent of resampling necessary to ensure that the measured values are representative of an average activity concentration for a full year.
Sch. 2 in force at 14.4.2016, see reg. 1(1)