rectly into a water distribution system without intervening storage. Direct use of reclaimed wastewater for human consumption, without the added protection provided by storage in the environment, is not currently a viable option for public water supplies. Instead, this report focuses on planned indirect potable reuse, which refers to the intentional augmentation of a community's raw water supply with treated municipal wastewater. The reclaimed water might be added to a water course, lake, water supply reservoir, or underground aquifer and then withdrawn downstream after mixing with the ambient water and undergoing modification by natural processes in the environment. The mix of reclaimed and ambient water is then subjected to conventional water treatment before entering the community's distribution system.
Planned indirect potable reuse cannot be considered in isolation from more general drinking water issues. Many communities currently use water sources of varying quality, including sources that receive significant upstream discharges of wastewater. In this sense, cities upstream of drinking water intakes are already providing water reclamation in their wastewater treatment facilities—for they treat the water, then release it into the raw water supply used by downstream communities. For example, more than two dozen major water utilities use water from rivers that receive wastewater discharges amounting to more than 50 percent of the stream flow during low flow conditions. Although most water systems using such raw water supplies meet current drinking water regulations, many of the concerns about planned, indirect potable reuse raised in this report also apply to these conventional water systems. The focus of this report, however, is planned indirect potable reuse of treated wastewater.
The several indirect potable reuse projects currently operating in the United States generally produce reclaimed water that meets or exceeds the quality of the raw waters those systems would use otherwise, as measured by current standards. In some instances the reclaimed water meets or exceeds federal drinking water standards established by the Safe Drinking Water Act. Current potable reuse projects and studies have demonstrated the capability to produce reclaimed water of excellent measurable quality and to ensure system reliability. In communities using reclaimed water where analytical testing, toxicological testing, and epidemiological studies have been conducted, significant health risks have not been identified. This suggests that reclaimed water can likely be used safely to supplement raw water supplies that are subject to further treatment in a drinking water treatment plant. However, these projects