We monitor it because it is a good indicator of the effectiveness of our filtration system. A routine sample and a repeat sample are total coliform positive, and one is also fecal or E.coli positive. The 90th percentile value means 90 percent of the homes tested have lead and copper levels below the given 90th percentile value. By-Product of Drinking Water Chlorination. Total Trihalomethanes is the sum of chloroform, bromodichloromethane, dibromochloromethane, and bromoform.
Compliance is based on the total.
New MCL effective December 16, 2001. We monitor it because it is a good indicator of the effectiveness of our filtration system. A routine sample and a repeat sample are total coliform positive, and one is also fecal or E.coli positive. The 90th percentile value means 90 percent of the homes tested have lead and copper levels below the given 90th percentile value. If the 90th percentile value is above the AL additional requirements must be met.