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Why Grey Water Systems Could Solve the World’s Water Scarcity Problems

Photo: Courtesy of Methi SOMÇAĞ
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Sharon Steiner

NSF International, Wastewater Treatment Unit Program Manager

This summer’s headlines brought to life dire water scarcity warnings that global public health organizations have been sounding for years.

Taps are dry in Chennai, India, forcing millions of people in one of the country’s largest cities to line up every day to fill buckets with their allowance of the basic, life-sustaining resource that has been shipped in via water trains and trucks.

A water crisis

Chennai’s story could play out in a number of cities around the world within the next couple of decades, or even the next few years. According to the United Nations, by 2025, 1.8 billion people will live in areas throughout the world with absolute water scarcity, and two-thirds of people could be living under water-stressed conditions.

Just 1 percent of the earth’s water is available for drinking and freshwater from the world’s underground aquifers is being extracted at unsustainable rates. Growth of megacities has pressured the world’s water supply, and major population centers like Mexico City; Cape Town, Africa; and Sao Paulo, Brazil have at times rationed water or cut back on the amount of water flowing from water sources.

Deforestation, pollution, prolonged droughts, and urbanization, as well as inefficient irrigation, water management, and wastewater treatment practices, are key factors in this looming humanitarian crisis.

Aging and crumbling infrastructure cause huge amounts of unnecessary waste, with an estimated 1 trillion gallons of treated water lost annually in the United States alone due to minor home water leaks, according to the U.S. Environmental Protection Agency.

Rising to the challenge

In response to the impending crisis, NSF International, a global public health standards organization, helped develop the standard NSF/ANSI 350: Onsite Residential and Commercial Water Reuse Treatment Systems to establish criteria for manufacturers to develop greywater reuse systems. The standard was developed using the American National Standards Institute process, which ensures balanced input from industry representatives, public health/regulatory officials and users/consumer representatives.

The NSF/ANSI 350 standard sets minimum requirements for greywater reuse treatment systems using water-saving technology. Instead of flushing toilets or watering lawns with drinking water, shower and laundry water is treated for these nonpotable functions.

A typical greywater reuse system certified to NSF/ANSI 350 standard requirements can save up to 1,500 gallons of freshwater daily and be scaled up for larger commercial reuse. These systems also earn credits toward LEED certification.

Testing to the standard is rigorous and is conducted over a 26-week period. Certification to NSF/ANSI 350 assures consumers and regulators that the treated greywater reduces particulates, risk of E. coli, and carbonaceous biochemical oxygen demand (CBOD5) to the required scientific effluent levels. As water scarcity and drought conditions persist globally, reuse of greywater, treated through a certified system, can help reduce human impact on our natural environment and conserve the world’s fresh drinking water. 

Sharon Steiner, NSF International, Wastewater Treatment Unit Program Manager, [email protected]

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