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.