The water distribution system serving the City of Topeka consists of a mixture of lined and unlined cast iron pipe. Consumer complaints involving red/rust-colored water and/or elevated turbidity levels started to occur in the mid 1980s and the Water Department initiated a monitoring plan in 1988 to assist in identifying the primary problem areas and to maintain detailed records of consumer complaints. The majority of the problems were found to occur in an area served by 4-inch and 6-inch unlined cast iron mains that are 50 to 70 years old. Several other areas with unlined mains that are located near the perimeter of the City's distribution system were also found to experience corrosion-related water quality problems. There are about 360 miles of unlined cast iron pipe in the system. Flushing programs conducted in all of these areas met with limited success so an analysis of treated water quality parameters versus red water complaints was conducted to determine whether modifications in the treatment process could be used to reduce the number of complaints. A treatment modification, conducted at plant scale testing, has been successful in lowering the number of complaints. However, the problem has not been eliminated so the City has embarked on an extensive pipe replacement program to insure the delivery of high quality water to its consumers. The analyses performed to identify potential water quality parameters for use in controlling plant operations are summarized in this paper.