In the early 1900s, sand-cast iron pipe was used almost exclusively for water distribution piping in the City of Edmonton, Alberta, Canada. During a period of rapid growth following World War II, a significant amount of cast iron pipe was installed, most of which was the spun-cast type. An increasing break frequency led to the decision to discontinue the use of cast iron pipe in 1965. The break frequency continued to increase throughout the 1970s and early 1980s and limited replacement of the most problematic sections of cast iron pipe was performed. In 1985, a peak of 1,600 water main breaks were recorded on 758 miles of pipe resulting in significant inconvenience to many customers. In response to the problem, a surcharge was introduced to the water bills of all customers in the City of Edmonton to specifically fund a cast iron water main replacement program. By the end of 1997, the capital program funded through the surcharge had expended over $70 million which resulted in a decrease in the length of cast iron water main to approximately 544 miles and a corresponding decrease in the annual number of breaks to 489. Aqualta, Edmonton's privatized water utility, is now shifting from a reactive to a proactive approach to managing the remaining cast iron pipe network. Alternative technologies such as cathodic protection are now being applied to some problematic pipe to reduce the rate of deterioration. The utility is also looking to the use of non-destructive testing for evaluation of pipe condition and artificial intelligence computer models for prediction of failure likelihood. This paper discusses Aqualta's cast iron water main replacement program. Includes reference, figures.