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People in developed countries use a substantial amount of water. According to the Environmental Protection Agency, the average American family of four uses over 1,500 litres of water every day. Most of that usage can be traced back to the bathroom, where water-intensive toilets, showers, and sinks are located.
While the water flushed down the toilet is known as blackwater, the wastewater drained from sinks, showers, bathtubs, and washing machines is known as greywater. Though greywater may contain traces of food, detergents, grease, and other potentially harmful pollutants or pathogens, it can be filtered, treated, and reused for other applications. Water may not seem like a finite resource for those in developed countries, but the UNESCO International Hydrological Programme has encouraged the recycling of greywater wherever possible to combat the global water crisis.
Numerous sustainable building projects around the world are incorporating greywater recycling systems into their designs for purposes like on-site landscaping irrigation. That's the vision outlined in the self-sustaining Hyperions project in India. Greywater can also be used for flushing toilets in jurisdictions that have adopted the International Plumbing Code. A residence using such a system could save up to 30% on their water usage.
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