In 1993, Tucson's Central Arizona Project aqueduct was completed. The city decided to use its Central Arizona Project allocation to supply water to half of its residents. The much anticipated CAP water resulted in disappointment and infrastructure problems. Within weeks of the change from groundwater to CAP water, residents in older parts of the city complained that the water was foul colored, tasted and smelled bad, and was corroding household appliances.
Because CAP water had a different mineral composition and pH from Tucson's groundwater, it effectively scoured the city's older pipes, removing rust and, in many cases, causing waterline breaks. The problems resulted from a combination of factors, including old plumbing and the manner in which Tucson treated the CAP water. In August 1994, the Tucson City Council voted to stop CAP water delivery to the most severely affected areas. The following January, City Council halted residential delivery of CAP water until the problems could be resolved. The city had received about 5,000 damage claims, so it temporarily reverted to strictly groundwater use until the problems could be solved.