| Classification System | Ionic Ratio |
| Good Quality Water | < 0.5 |
| Slightly Contaminated | 0.5 - 1.3 |
| Moderately Contaminated | 1.3 - 2.8 |
| Injuriously Contaminated | 2.8 - 6.6 |
| Highly Contaminated | >15.5 |