Clean water is a resource that is scarcer than many people in the developed world realize. After accounting for saltwater and water trapped in glaciers, just 1% of the Earth’s water is fresh—including the water in underground aquifers and the soil.
And even that 1% is not guaranteed. Water shortages due to drought, lack of sources or population expansion are becoming ever more common, and control of water resources already is a point of contention along the touch-and-go borders between some countries, including India and Pakistan, and Turkey and Syria. All of this creates urgency to find ways of securing a steady, plentiful supply of clean water.
This urgency translates into what some originally saw as a wild solution: turning wastewater into clean drinking water, generally through a three-step process of microfiltration, reverse osmosis and ultraviolet treatment. There were and are multiple challenges with this, ranging from psychological—for many people, the idea of drinking treated wastewater is unfathomable—to regulatory.
In the U.S., no national regulations or criteria have been developed or proposed for direct potable reuse—reclaimed wastewater that flows directly from a treatment facility to people’s taps—although a 2012 report on water reuse guidelines from the U.S. Environmental Protection Agency acknowledges that it “may be a reasonable option, based on significant advances in treatment technology and monitoring methodology in the last decade and health effects data from [indirect potable reuse] projects and [direct potable reuse] demonstration facilities.” The report referenced examples where indirect potable reuse is working: In Gwinnett County, Ga., treated effluent is discharged to Lake Lanier, where the county and area communities get their potable water.
In September 2013, San Diego considered taking wastewater from a plant that was not meeting federal standards for secondary treatment and—instead of putting nonexistent money into updates—diverting the wastewater to another site to be purified into tapwater. This would shave $434 million off the cost of upgrading the plant and reclaim more than 100 million gal of wastewater per day for purification. Perhaps the best news was the surprising public opinion: A poll conducted by a San Diego State University researcher found that 73% of respondents supported the conversion to potable use, possibly due in part to the city’s intensive 2010 PR campaign for a wastewater purification demonstration project that admonished, “The Yuck Factor: Get Over It!”
If San Diego is any indication, public sentiment is turning toward greater acceptance of potable reuse of treated wastewater, especially as it becomes more apparent to the average citizen that water is not an endlessly abundant natural resource. The technology behind potable reuse has been realized, but what has yet to happen is just as weighty a task: public outreach. Any state or country looking to expand its drinking water supply by treating wastewater needs to invest in educating the consumers. Without public support, any “toilet to tap” movement will be dead in the water.