| Parameter | Proficiency testing item N178A | Uncertainty | Proficiency testing item N178B | Uncertainty | Unit |
| Electr. conductivity (25 °C) | 497 | 2 | 441 | 1 | µS/cm |
| Total hardness | 1.823 | 0.018 | 1.739 | 0.016 | mmol/L |
| Alkalinity KS 4.3 (as H+) | 1.045 | 0.013 | 1.506 | 0.018 | mmol/L |
| Hydrogen carbonate | 60.7 | 0.8 | 88.8 | 1.1 | mg/L |
| Calcium | 42.1 | 0.6 | 31.3 | 0.5 | mg/L |
| Magnesium | 18.8 | 0.2 | 23.3 | 0.3 | mg/L |
| Sodium | 20.19 | 0.17 | 14.6 | 0.2 | mg/L |
| Potassium | 3.81 | 0.03 | 5.47 | 0.04 | mg/L |
| Nitrate (as NO3) | 59.3 | 1.5 | 75.7 | 1.5 | mg/L |
| Nitrite (as NO2) | 0.0525 | 0.0015 | 0.0710 | 0.0013 | mg/L |
| Ammonium (as NH4) | 0.0355 | 0.0050 | <0.01 | - | mg/L |
| Chloride | 48.3 | 0.6 | 14.00 | 0.18 | mg/L |
| Sulphate (as SO4) | 59.3 | 0.7 | 53.4 | 0.6 | mg/L |
| Orthophosphate (as PO4) | <0.009 | - | 0.0304 | 0.0017 | mg/L |
| Boron | 0.0454 | 0.0006 | 0.0604 | 0.0013 | mg/L |
| DOC (as C) | 5.43 | 0.03 | 2.067 | 0.013 | mg/L |
| Total phosphate (as PO4) | <0.009 | - | 0.0489 | 0.0013 | mg/L |
| Free Cyanide | 0.0456 | 0.0003 | 0.0555 | 0.0003 | mg/L |
| Silicon | 2.775 | 0.016 | 6.05 | 0.03 | mg/L |
| Fluoride | 0.3028 | 0.0012 | 0.792 | 0.003 | mg/L |