Wastewater from sewage treatment plants is one of the largest potential sources of freshwater where supplies are limited. About 60% to 90% of the potable water delivered to urban residents in the United States is discharged into sewage collection systems. After it has been treated to kill pathogens and remove contaminants, it can be reused for irrigation and industrial use, and to maintain stream flow.

Indirect reuse of treated municipal wastewater is becoming increasingly attractive to many municipalities, especially in the West. The Orange County Water District in California injects treated wastewater from a sewage treatment plant into its water supply aquifer to prevent the intrusion of salt water. Throughout California, construction is already underway on a number of reclamation facilities to provide reclaimed water for irrigation, and landscape and lawn watering. When completed, the program will serve an area of more than 700 square miles, providing 50,000 acre-feet of reclaimed water annually to local water supplies. Facilities will include up to eleven new or expanded water reclamation plants, state-of-the-art water purification plants, and hundreds of miles of reclaimed water delivery pipelines.

TABLE 8.2
The five realities of water in the West
SOURCE: "The Five Realities," in Water 2025: Preventing Crises and Conflict in the West, U.S. Department of the Interior, Bureau of Reclamation, May 2003, http://www.doi.gov/water2025/index.html (accessed April 13, 2005)