| Sodium | Chloride | Sulphate | Dissolved iron | Dissolved manganese | Arsenic | Total dissolved solids | |
|---|---|---|---|---|---|---|---|
| Median | 15 | 15.3 | 6.5 | 0.03 | 0.01 | 0 | 149 |
| Range | 4.6–117 | 2.8–142 | 0.1–44 | 0–5.5 | 0–3.6 | 0–0.24 | 64–950 |
| Guideline level | 200 | 250 | 250 | 0.2 | 0.04 0.4* | 0.01* | 1,000 |
| Percentage of sites exceeding guideline (%) | 1.9% | 2.5% | 0% | 26.5% | 33% 15%* | 10.2% | 4.3% |
Notes:
(1) Units are in milligrams per litre.
(2) Guideline levels are for aesthetic quality defined by the drinking water standards for New Zealand unless otherwise stated (Ministry of Health, 2005).
(3) Numbers with asterisks (*) relate to health guidelines (drinking water standards for New Zealand maximum acceptable value (Ministry of Health, 2005)) not aesthetic quality.
Source: Adapted from Ministry for the Environment, in press b.
Table 10.1: National medians and ranges for minerals, chemicals, and metals in monitored groundwater, 1995–2006
March 2021
© Ministry for the Environment