| Standard DRASTIC vulnerability category | Nitrate concentration (mg/l) | COP vulnerability category | Nitrate concentration (mg/l) | ||
| Dry season | Wet season | Dry season | Wet season | ||
| V. Low | <2 | 0 - 20 | V. Low | 0 - 2 | 20 - 30 |
| Low | 2 - 4 | 20 - 30 | Low | >10 | > 30 |
| Medium | >10 | >30 | Moderate | >10 | >30 |
| High | >10 | >30 | High | >10 | >30 |