It has been demonstrated recently that the presence of copper in solutionenhances trihalomethane (THM) formation. Copper is known to catalyze a number of reactions that are similar to the conventional haloform formation. A study was therefore initiated to investigate the specific role played by copper in the formation of chloroform during chlorination of water supplies. Aqueous solutions containing a number of known THM precursors were subjected to chlorination in the presence and absence of copper,and subjected to time-course monitoring of THM concentration. Includes 20 references, figures.