Trihalomethane concentrations in tap water (μg/l) from residences and other locations in Orange County, North Carolina from two data sources
| b* | n* | N* | Mean | Median | Min | Max | SD | |
|---|---|---|---|---|---|---|---|---|
| *b = no. of sampled locations (or households); n = no. of measurements per location; N = total number of measurements. | ||||||||
| †In the three surveys conducted in 1995, measurements were only reported for total trihalomethane levels. | ||||||||
| Exposure assessment study (7/94–10/94) | ||||||||
| Chloroform | 17 | 3–4 | 56 | 62.3 | 56.5 | 30.2 | 141 | 23.1 |
| Bromodichloromethane | 17 | 3–4 | 56 | 14.3 | 13.4 | 9.41 | 19.7 | 3.32 |
| Dibromochloromethane | 17 | 3–4 | 56 | 3.08 | 2.26 | 1.48 | 5.86 | 1.46 |
| Total trihalomethanes | 17 | 3–4 | 56 | 79.7 | 75.0 | 41.7 | 161 | 24.0 |
| Exposure assessment study (7/94–4/95)† | ||||||||
| Total trihalomethanes | 17 | 6–7 | 107 | 71.1 | 67.5 | 41.7 | 161 | 21.7 |
| Routine monitoring data (2/91–11/95) | ||||||||
| Chloroform | 5 | 20 | 100 | 46.9 | 41.1 | 22.4 | 128 | 21.0 |
| Bromodichloromethane | 5 | 20 | 100 | 9.38 | 8.95 | 4.00 | 19.7 | 3.07 |
| Dibromochloromethane | 5 | 20 | 100 | 1.48 | 1.20 | <1 | 3.70 | 0.734 |
| Total trihalomethanes | 5 | 20 | 100 | 57.7 | 52.2 | 27.4 | 142 | 23.3 |
| Routine monitoring data (3/94–11/95) | ||||||||
| Chloroform | 5 | 8 | 40 | 44.4 | 40.7 | 23.4 | 98.3 | 18.5 |
| Bromodichloromethane | 5 | 8 | 40 | 10.4 | 10.2 | 5.60 | 16.1 | 2.34 |
| Dibromochloromethane | 5 | 8 | 40 | 1.95 | 1.80 | <1 | 3.70 | 0.697 |
| Total trihalomethanes | 5 | 8 | 40 | 56.8 | 52.3 | 30.6 | 114 | 20.3 |