| Standard DRASTIC Vulnerability Category | Nitrate Concentration (mg/l) | Modified DRASTIC 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 | 0 - 2 | 20 - 30 | Low | >10 | > 20 |
| Medium | >10 | >30 | Moderate | >10 | > 30 |
| High | >10 | >30 | High | >10 | >30 |