AWWA JAW21955

This survey was conducted to determine the extent and costs of compliance with the existing maximum contaminant level (MCL) for trihalomethanes (THMs). It was found, on average, that the MCL of 0.10 mg/L had reduced the concentrations of THMs in larger utility systems by 40-50 percent. About 4.6 percent of the responding utilities had exceeded the MCL at least once during the period 1984-1986. Compliance with the THM regulation involved estimated capital expenditures of $31-102 million and yearly operating and maintenance costs of $8-29 million for utilities serving more than 10,000 people. Approximately 75 percent of the water quality managers responding believed that the MCL should not be reduced below 0.10 mg/L. Only four states require that smaller utilities (those serving fewer than 10,000 people) monitor for THMs. Includes 9 references, tables, figures.