Labortory investigations backed by field studies of two North Carolina water systems explored the potential for chloroform formation as a function of raw water characteristics and chlorination practices and examined the efficiency of various coagulants in removing organic chloroform precursors. The objectives of this study were to determine the influence of raw water characteristics on chloroform formation in Durham and Chapel Hill drinking water, to determine by laboratory experimentation the effect of pretreatment on the removal of chloroform precursors, and to determine the effect of full-scale water treatment plant modifications on the production of chloroform.