Indirect reuse of treated wastewater effluents (non-potable) often occurs following discharge to receiving waters that provide natural dilution and then later processed for other uses. More direct reuse of highly treated or reclaimed wastewater for augmentation of surface and groundwater supply and use is now being studied and considered at many locations due to a combination of factors including: water supply shortages, water conservation concerns and economics. As the demand for water supply outstrips the capacity of existing supplies and the development of additional sources is not feasible, reuse of treated wastewater will become increasingly important. The DEQ is developing regulations entitled, "Wastewater Reclamation and Reuse" that will provide standards for the use of wastewater treated to defined levels of quality.
The use of non-potable effluents for landscape irrigation and equipment washing has routinely been provided for in the discharge permits issued to treatment works. More frequently, reuse involves irrigation of golf courses and other areas open to controlled public access. The reuse of wastewater with more opportunity for public exposure will require the use of advanced wastewater treatment technologies such as, chemically enhanced pollutant removal, filtration, absorption with activated carbon and ion-exchange with specific media, to provide an acceptable level of health and environmental protection. The filtration unit operations are especially critical to removing disinfection resistant forms of pathogenic microorganisms such as cysts and spores of protozoa (giardia and cryptosporidia). Absorption unit operations employing activated carbon are necessary to remove toxic synthetic organic compounds and the precursor compounds that could produce chlorinated organics. However, national standards have not been established for the renovation and reclamation of treated wastewater for reuse. Risk assessment studies are now underway to provide a scientific basis on which wastewater reuse standards can be developed. In addition, operational experience on infrastructure needs and marketing requirements is being developed through reuse demonstrations now operating throughout the continental states. Direct reuse to augment water supplies withdrawn for drinking water treatment (recycling) would require the level of safeguards now provided for the Occoquan Reservoir located in Northern Virginia. The Occoquan Reservoir furnishes a water supply that is treated and distributed as drinking water to hundreds of thousands of Virginia residents. The stream flow to the reservoir contains a significant portion of diluted, renovated wastewater discharged from the advanced wastewater reclamation facility operated by the Upper Occoquan Sanitary Authority (UOSA).