A new strategy for drought-stressed cities: graywater recycling
Many regions of the United States are struggling with water shortages. Large areas of the West are contending with moderate to severe drought, while California is now in the fifth year of one of the most extreme droughts in its history. Even non-arid regions, such as the Southeast, are not exempt from water shortages. At the same time, rapid population growth is increasing water demand in many of the nation’s most water-scarce regions, including California, Nevada, Arizona, Texas and Florida.
In these conditions, some state and local governments are looking for innovative ways to save water. One strategy gaining increasing attention is using graywater – water from bathroom sinks, showers, bathtubs, clothes washers and laundry sinks, but not from toilets or kitchens – for purposes other than drinking, such as flushing toilets.
The National Academies of Sciences, Engineering, and Medicine recently published a report that analyzes the potential of graywater reuse, available treatment technologies and the human health and environmental risks associated with graywater reuse. The study’s committee, on which I served, concluded that reusing graywater can improve water conservation by expanding local water supplies and providing a drought-resistant year-round local water source.
In drought-stricken regions, households and businesses have already started to reuse graywater, and some builders are installing dual plumbing systems in new developments to supply treated graywater for toilet flushing and possibly other nonpotable uses, such as watering gardens. Rather than being sent down the drain, water from showers or sinks is stored in dedicated tanks and treated depending on how it will be used on site.
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