water for irrigation could save between 25 percent and 40 percent of drinkable water for human consumption. Its impact on whole communities would be economically favorable, reducing the size of the water-purification plants and sewage-treatment facilities required.
The composition of gray water varies depending on several factors: the source of the water; the plumbing system involved; the life style of the home occupants; and the personal hygiene habits of the occupants (Coder, 2001). It will depend upon the types of cleaning products used such as soaps, laundry detergents and household cleaners, and the cleaning habits of the home's occupants. This means that the physical, chemical and biological characteristics of gray water will vary from home to home and business to business. Household gray water typically contains high levels of grease and a large amount of particles and fibers which must be removed before the water is reused.
Washing machines typically yield from 30 to 40 gallons of gray water per load (Questions About Gray Water, 1990). The yield from showers depends on the flow rate: for low flow rate shower heads, the average yield is two to three gallons per minute, and for regular shower heads, from five to 8 gallons per minute. The average weekly yield from a bathroom sink is roughly 14 gallons per person. This indicates the tremendous water savings which can be brought about by reusing gray water for irrigation purposes.
Household systems are available for the storage and reuse of gray water (Innis, 2001). The plumbing apparatus is quite simple, and water is diverted from sinks, bathtubs and laundry rooms into a holding tank. Gray water systems are installed on a house-by-house basis rather than at the community level (Water Reuse, 2001). Some large hotels install them and use the gray water as the water supply for flushing toilets. A gray water system for a new home costs anywhere from a few hundred ...