"Water reuse" is the use of wastewater or water reclaimed from one application, such as municipal wastewater treatment, for another application, such as landscape watering. It is important that the reused water comply with all federal, state, and local laws and regulations. Some of the possible applications for the reuse of wastewater include industrial applications; landscape irrigation; agricultural irrigation; aesthetic uses, such as fountains in parks or cities; and fire suppression.
Several factors must be considered in any wastewater reuse program, including the quality of the water needed for the application, the identification of the wastewater source that meets this quality level, and the very practical needs of transporting this water to its new use.
The practical benefit of wastewater reuse (or reclaimed water) is that it reduces the need for surface water or groundwater. The reuse of water provides for conservation of new potable water sources as well as elimination of the need to expand treatment and processing facilities.
Water recycling is a part of water reuse. Recycling of water is the reuse of water for the same application for which it was originally used. In some cases, the recycled water requires treatment before it can be used again. The factors to be considered in a water recycling program are similar to the ones listed above for wastewater reuse. A very common example of water recycling is the circulation of cooling water. This represents a very large use of water in the United States. Water is passed through a system to lower the temperature of a heat source, then the water is discharged. Recycling the water, via a recirculating cooling system, can greatly reduce water use and still perform the cooling operation required.
MARK G. ROBSON
Environmental Protection Agency (2000). Cleaner Water Through Conservation. Available at http://www.epa.gov/OWOW/NPS/chap3.html.