Regulatory Perspective on Water Reuse

Our natural water resources are being stretched to the limit due to population growth, droughts, and climate changes. Water reuse is increasingly being included as an integral component of water resources management in many parts of the country. The use of reclaimed water for both many applications is well established in states such as Arizona, California, Florida, and Texas and is becoming more prevalent in areas not historically deemed to be water-short. Reclaimed water is used for nonpotable applications ranging from pasture irrigation to food crop irrigation, and the use of reclaimed water for potable reuse via groundwater recharge and surface water augmentation is experiencing a surge in both the number of existing and planned projects.Several states have adopted reclaimed water regulations, and regulations among the states vary considerably. Water reuse criteria are principally directed at public health and environmental protection. Making reclaimed water acceptable for reuse applications is achieved by eliminating or reducing the concentrations of potentially hazardous constituents through source control, wastewater treatment, and/or by limiting human exposure to the water via design or operational controls. Most health-related concerns and issues associated with the use of reclaimed water are resolvable using conventional treatment technology, proper operation and management strategies, and use area controls. For nonpotable uses of reclaimed water, the contaminants of greatest concern are microbial pathogens, while both microbial and chemical contaminants need to be considered for potable reuse. Nonpotable water reuse criteria become more restrictive as human contact with the reclaimed water increases, and a high degree of treatment typically is required for uses where the public or workers are likely (or expected) to come in contact with the water. For high level nonpotable uses such as the irrigation of food crops eaten raw or the irrigation on residential property, many states require that the effluent contain few or no measurable levels of pathogens. Regulations for potable reuse typically require that the reclaimed water meet drinking water standards, and some states require additional monitoring for selected unregulated chemical constituents that may include endocrine disrupting compounds, pharmaceuticals, and personal care products.This presentation is focused on the public health aspects of water reuse and the rationale for the various regulatory requirements. Potable reuse will be discussed, particularly the need to reduce or remove health-significant organic constituents.