slide 1

Water-supply system Treatment slide 2 Ambientgroundwater Watercaptured by supply wells Drinkingwater

slide 3 Hawaii Oahu Alaska No VOC Detection VOC Detection

VOC concentrations in aquifers Not detected Detected, below 1 ppb slide 4 Detected, above 1 ppb

Chloroform was the most frequently detected VOC in aquifer samples slide 5 DETECTION FREQUENCY, IN PERCENT Toluene TCE PCE Chloroform 02468MTBE

PCE and TCE were also frequently detected in aquifer samples slide 6 DETECTION FREQUENCY, IN PERCENT Toluene TCE PCE Chloroform 02468MTBE

MTBE was the third most frequently detected VOC in aquifer samples slide 7 DETECTION FREQUENCY, IN PERCENT Toluene TCE PCE Chloroform MTBE

Domestic wells slide 8 Public wells and

slide 9 Hawaii Oahu Alaska No VOC Detection Concentration less than MCL or HBSL Concentration greater than MCL

Public wells Domestic wells DETECTION FREQUENCY, IN PERCENT concentrations below MCLs and HBSLs concentrations greater than MCLs slide 10

VOCs with concentrations greater than MCLs slide 11 DBCPX 1,2-DichloropropaneX EDBX 1,1-DichloroetheneXX Vinyl chlorideX TCEXX PCEXX Methylene chlorideX Domestic Compound Public Well type Fumigants Chemical production Solvents Group

THMs in domestic and public wells Chloroform Bromodichloromethane Dibromochloromethane Bromoform DETECTION FREQUENCY, IN PERCENT slide 12 Domestic Public

Summary Widespread occurrence of VOCs Concentrations seldom of potential concern Large number of vulnerable aquifers slide 13