11.—(1) A local authority must monitor each private water supply in its area (other than a supply covered by paragraph (8)) for the parameters specified in Table D in Part 3 of Schedule 1 (“the radioactive parameters table”) in accordance with paragraphs (2) to (7) and (9).
(2) As regards the indicative dose parameter, the local authority—
(a)must carry out monitoring where an artificial source of radionuclides or elevated natural radioactivity is present and it cannot be shown on the basis of other surveillance programmes or investigations that the level of indicative dose is below the value specified in the radioactive parameters table;
(b)may use a screening strategy for gross alpha and gross beta activity or for individual radionuclides and, in the event that there is any exceedance of the value specified in that Table, must carry out an analysis of the specific radionuclides in accordance with Part 3 of Schedule 3.
(3) As regards the radon parameter, the local authority must—
(a)ensure a representative survey is carried out in accordance with paragraph (4) to determine the likelihood of a supply failing the value specified in the radioactive parameters table;
(b)carry out monitoring where there is reason to believe, on the basis of the results of the representative survey or other reliable information, that the parametric value for radon might be exceeded.
(4) 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 (in particular 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.
(5) As regards the tritium parameter, the local authority must carry out—
(a)monitoring, where an anthropogenic source of tritium or other artificial radionuclides is present within the catchment area and it cannot be shown on the basis of other surveillance programmes or investigations that the level of tritium is below the value specified in the radioactive parameters table;
(b)an investigation of the presence of other artificial radionuclides, where the concentration of tritium exceeds its parametric value.
(6) In the case of a private water supply to which regulation 9 applies, where monitoring is required by paragraph (2) or (5), it must be carried out at the frequencies as set out for audit monitoring in Table 3 in Part 2 of Schedule 2.
(7) In the case of a private water supply to which regulation 8 or 10(1) applies (but excluding a supply covered by paragraph (8)), where monitoring is required by paragraph (2) or (5), it must be carried out at least every 5 years and more frequently if the risk assessment shows this to be necessary.
(8) In the case of a private water supply to a single dwelling not provided as part of a commercial or public activity, a local authority may monitor the supply in accordance with paragraphs (2) to (5), and must do so if requested to do so by the owner or occupier of that dwelling.
(9) Where a parametric value is exceeded in a particular sample, the local authority must define the extent of re-sampling necessary to ensure that the measured values are representative of an average activity concentration for a full year.
(10) The local authority may, for such time as it may decide, exclude from monitoring a parameter contained in the radioactive parameters table—
(a)if it considers that the parameter in question is unlikely to be present in the supply or system at a concentration or value that poses a risk of the private water supply failing to meet the concentration, value or state specified in the radioactive parameters table in respect of that parameter,
(b)taking into account the findings of any risk assessment, and
(c)taking into account any guidance issued by the Secretary of State.
(11) The local authority must provide the Secretary of State with the grounds for a decision under paragraph (10) and the necessary documentation supporting the decision (including the findings of any surveys, monitoring or investigations carried out).
(12) The Secretary of State must communicate to the European Commission the grounds for a decision under paragraph (10) and the information provided under paragraph (11).