The demand for drinking water in cities and the lack of new water sources have spurred water conservation and recycling measures over the last 30 years. Need, coupled with advances in water treatment technology, is motivating a small but growing number of cities to use reclaimed waste water to supplement drinking-water supplies. But, important questions remain regarding the level of treatment, monitoring, and testing needed to ensure public safety.
In its new report, Issues in Potable Water Reuse, a National Research Council committee concluded that reclaimed waste water can be used to supplement drinking-water sources, but only as a last resort and after a thorough health and safety evaluation. Municipalities first must fully assess health impacts from likely contaminants and develop comprehensive systems for monitoring, testing, and treatment. Other water sources and conservation measures also should be tried to the extent practical, before turning to reclaimed waste water.
Because regulations for safe drinking water were not developed with reclaimed water in mind, they may not be the best standard for testing its quality, the committee said. Reclaimed water may contain sources of contamination that cannot be determined through current testing or treatment processes.
When considering reclaimed waste water for public water supplies, the report
distinguishes between direct and indirect use. Adding highly treated waste
water directly into a water supply without storing it first in a reservoir is
not a viable option. Indirect use is viable, however, and that approach was
examined by the committee. Indirect use augments the drinking-water supply by
adding reclaimed treated water first to a lake, reservoir, or underground
aquifer. The mixture of natural and reclaimed water is then subjected to normal
water treatment before it is distributed as drinking water
Contact: Ellen Bailey Pippenger, Dumi Ndlovu
The National Academies