Guaranteeing a safe and continuous drinking water supply for the city of Cali, Colombia, has become a concern for the water company of Cali, the environmental authorities, universities, and entities involved in the water resource. The progressive deterioration of the city’s water sources has led to a search for future water sources and/or technologies in order to ensure high water quality standards at minimal costs. This paper describes a variety of problems occurring in the current water supply system in Cali and gives a description of the alternatives that have been considered to solve these problems in the past decades. Multi-criteria analysis was applied to assess alternatives for safe drinking supplies, demonstrating their suitability during the decision-making process when constraints arise due to political, community and institutional interests.