There are two types of organic contaminants, including volatile and synthetic. The volatile organic chemicals include acrylamide, benzene, carbon tetrachloride, chlorobenzene, o-dichlorobenzene, p-dichlorobenzene, 1.2-dichloroethane, 1.1-dichloroethylene, cis- and trans-1.2 dichloroethylene, dichloromethane, 1.2-dichloropropane, xylenes, epichlorohydrin, ethylbenzene, styrene, tetrachloroethylene, toluene, 1.2.4-tricholorobenzene, 1.1.1-tricholorethane, 1.1.2-trichloroethane, trichloroethylene, and vinyl chloride. The synthetic organic chemicals include adipate, alachlor, aldicarb/aldicarb metabolites, atrazine, benzo(a)pyrene, carbofuran, chlordane, 2.4-D, dalapon, dibromochloropropane, dinoseb, dioxin (2.3.7.8-TCDD), diquat, endothall, endrin, ethylene dibromide, glyphosate, heptachlor/heptachlor epoxide, hexachlorobenzene, hexachlorocyclopentadiene, lindane, methoxychior, oxamyl, pentachlorophenol, phthalate, di(2-ethylhexyl), picloram, polychlorinated biphenyls, simazine, toxaphene, 2.4.5-TP.
Carbon-based chemicals, such as solvents and pesticides, which can enter drinking water supplies through runoff from cropland, discharges from industrial operations, underground tanks, spills and other sources.