This paper presents a study on the consumption of free chlorine and chloramines and formation of disinfection byproducts in the presence of pipe deposits collected from cities with ductile iron pipe distribution systems. Several characteristics of the deposit material were determined, including surface area, reduced iron content, and organic and inorganic carbon content. Several methods were used to estimate organic carbon content: NaOH and acetone extraction, as well as direct combustion. Experiments were conducted with crushed and whole deposits in batch reactors, and with whole deposits in continuous flow reactors which allowed control of the system hydrodynamics. Includes 9 references.