Total trihalomethane (μg/l) data for 96 Massachusetts communities
| Period | 25th centile | Median | 75th centile | 90th centile |
|---|---|---|---|---|
| 1989 | ||||
| April–June | 9.7 | 25.5 | 40.5 | 59.0 |
| July–September | 11.0 | 34.8 | 53.0 | 81.6 |
| October–December | 9.5 | 27.9 | 51.0 | 64.5 |
| 1990 | ||||
| January–March | 9.1 | 25.5 | 47.6 | 61.3 |
| April–June | 13.0 | 26.5 | 51.8 | 64.8 |
| July–September | 14.2 | 32.7 | 55.8 | 83.7 |
| October–December | 11.5 | 28.3 | 50.3 | 67.7 |