Waste Not: Recycled Water is the Future
By Iva Fedorka
Many consider water a free, natural resource, but collecting, purifying, storing and distributing water costs billions of dollars annually. And because recycling efforts to increase supply and reduce costs are not regulated at the federal level, occasional contamination crises, like the high levels of lead found in drinking water in Flint, Michigan, never fail to raise concerns.
Although the water in oceans is abundant, its salt content makes it undrinkable. Eliminate the water trapped in glaciers and icecaps, and only about one percent of all the world’s water is fresh. A very small portion of that fresh water is found in waterways, with the remainder trapped in soil or aquifers. Regional and local water shortages have become increasingly common, and access to water is also becoming an international issue, with adjoining countries competing for limited resources.
A Battery of Tests to Support Regulations
In the United States, the regulation of water and wastewater is federally mandated by the Environmental Protection Agency (EPA). As part of the Clean Water Act (CWA), the EPA oversees wastewater discharge and treatment, and the National Pollutant Discharge Elimination System (NPDES) issues permits that establish specific discharge limits, requirements for monitoring and reporting, and other measures to ensure that pollutants do not harm the environment. Under the Safe Drinking Water Act (SDWA), the EPA sets drinking water quality standards and oversees the states, localities and water suppliers that implement them.
To fulfill regulatory requirements, approximately 100 substances are measured in ambient water, drinking water and wastewater. Some water testing is focused on nutrients and microorganisms such as bacteria, viruses, protozoa and parasites. Chemical contaminants may occur naturally or can be introduced by man; these include nitrogen, bleach, salts, pesticides and metal, and compounds found in pharmaceuticals and personal care products.
Other tests detect physical contaminants — like sediment or suspended organic materials from soil erosion — that affect the appearance or properties of water. And water can contain natural or introduced radiological contaminants, like cesium, plutonium and uranium.
Recycling Requires Rethinking
The costs for testing and treating water and wastewater can be reduced when either is conserved or recycled. Since all water is continuously “re-used” through the hydrologic cycle of precipitation, condensation and evaporation, there may be shortcuts or reuse opportunities yet to be identified within that cycle. “Graywater” from sinks and showers does not constitute “wastewater” and can be used, untreated, for irrigation. “Blackwater” (actual sewage) can be treated to become “reclaimed water” that is suitable for irrigating parks, golf courses, cemeteries and other landscaping. This recycled water is also used for steam turbines or industrial machinery. Some communities have moved all the way to 100% recycling and retain and repurpose all of their wastewater.
A better understanding of exactly how wastewater is treated could increase public support for recycling. When a toilet is flushed, its contents are carried via sewer to a municipal wastewater plant where grates or screens are used to separate any large, solid material from the liquid. The liquids are then placed into a settling tank where smaller solids fall to the bottom and oils rise to the surface. Next, the wastewater moves to an aeration tank where the oxygen helps microbes digest the waste further. After a final settling step, the clarified water is treated with antimicrobial ultraviolet light or chlorine to kill any remaining microorganisms before the water is released.
“In essence, there is no wastewater, just wasted water,” said Ben Grumbles, president of the U.S. Water Alliance and a member of the Water Science and Technology Board. To Grumbles’ point, successful water recycling programs require a paradigm shift: “used” or “waste” water can become a valuable resource rather than something to dispose of. Studies have also shown that chemical levels and pathogens in existing water supplies and recycled water are essentially equivalent, and sometimes lower.
“The fact is, people already drink reused water,” said Ken Herd, the Water Supply Program Director for the Southwest Florida district. But currently there are neither national standards for, nor great interest in, water reuse.
- Do you or your community recycle water? If so, how?
- What other instances of water contamination have happened in the United States?
- Environmental Protection Agency