The National Academy of Sciences, America's leading body of objective researchers, recently reported that American cities release "Approximately 12 billion gallons of municipal wastewater effluent each day to an ocean or estuary out of 32 billion gallons per day discharged nationwide." Their report, grippingly titled, Water Reuse: Potential for Expanding the Nation's Water Supply Through Reuse of Municipal Wastewater doesn't just emphasize waste water reuse, it clearly states waste water may be cleaner in some cities. From the exec. summary --
"Expanding water reuse—the use of treated wastewater for beneficial purposes including irrigation, industrial uses, and drinking water augmentation—could significantly increase the nation’s total available water resources, this new report finds. A portfolio of treatment options is available to mitigate water quality issues in reclaimed water, and new analysis suggests the risk of exposure to certain microbial and chemical contaminants from drinking reclaimed water does not appear to be any higher than the risk experienced in at least some current drinking water treatment systems and may be orders of magnitude lower. Adjustments to the federal regulatory framework could enhance public health protection for both planned and unplanned (or de facto) reuse, and increase public confidence in water reuse.
Read the full report here.