1.—(1) A local authority must undertake check monitoring in accordance with this Part.
(2) “Check monitoring” means sampling for each parameter listed in Table 1 in the circumstances listed in that Table in order to—
(a)determine whether or not water complies with the concentrations or values in Schedule 1,
(b)provide information on the organoleptic and microbiological quality of the water, and
(c)establish the effectiveness of the treatment of the water, including disinfection.
| Parameter | Circumstances |
|---|---|
| Aluminium | When used as flocculant or where the water originates from, or is influenced by, surface waters |
| Ammonium | In all supplies |
| Clostridium perfringens (including spores) | Where the water originates from, or is influenced by, surface waters |
| Coliform bacteria | In all supplies |
| Colony counts | In all supplies |
| Colour | In all supplies |
| Conductivity | In all supplies |
| Escherichia coli (E. coli) | In all supplies |
| Hydrogen ion | In all supplies |
| Iron | When used as flocculant or where the water originates from, or is influenced by, surface waters |
| Manganese | Where the water originates from, or is influenced by, surface waters |
| Nitrate | When chloramination is practised |
| Nitrite | When chloramination is practised |
| Odour | In all supplies |
| Pseudomonas aeruginosa | Only in the case of water in bottles or containers |
| Taste | In all supplies |
| Turbidity | In all supplies |
2.—(1) Sampling must be carried out at the frequencies specified in Table 2.
| Volume m3/day | Sampling frequency per year |
|---|---|
| ≤ 10 | 1 |
| > 10 ≤ 100 | 2 |
| > 100 ≤ 1,000 | 4 |
| > 1,000 ≤ 2,000 | 10 |
| > 2,000 ≤ 3,000 | 13 |
| > 3,000 ≤ 4,000 | 16 |
| > 4,000 ≤ 5,000 | 19 |
| > 5,000 ≤ 6,000 | 22 |
| > 6,000 ≤ 7,000 | 25 |
| > 7,000 ≤ 8,000 | 28 |
| > 8,000 ≤ 9,000 | 31 |
| > 9,000 ≤ 10,000 | 34 |
| > 10,000 | 4 + 3 for each 1,000m3/day of the total volume (rounding up to the nearest multiple of 1,000m3/day) |
(2) A local authority may reduce the frequency of sampling for a parameter to a frequency not less than half if the local authority is of the opinion that the quality of water in the supply is unlikely to deteriorate and—
(a)in the case of the hydrogen ion parameter, the supply has no pH value that is below 6.5 and above 9.5;
(b)in all other cases, in each of two successive years the results of samples taken for the purposes of monitoring the parameter in question are constant and significantly lower than the concentrations or values referred to in Schedule 1.
(3) The local authority may set a higher frequency for any parameter if it considers it appropriate, taking into account the findings of any risk assessment, and may monitor anything else identified in the risk assessment.