Graywater is the referring to any used water from a household, except water from the toilet. Wastewater from laundry can also be included, if biodegradable soaps have been used for the laundry.
Since greywater can account for up to 60% of household wastewater, if it is recycled and used a second time, a considerable impact can be made in terms of conservation of this precious resource.
Population growth in many countries is putting greater and greater demands on regional water supply. As development accelerates, in addition to scarcity, pollution of existing water, as well as drought and increased flooding linked to global warming patterns, impact the amount of fresh water available.
Many politicians, long-range planners, and futurists warn that water wars will emerge to supplant oil as a cause of international conflict and war.
Safety of Greywater
There has been some worry about the safety of graywater use, and some building codes prohibit it. The concern is that disease may be spread from wastewater, particularly from food particles, which is why some definitions of grey-water exclude kitchen wastewater. However, there has been little evidence of disease spread found in ornamental landscapes, as not many water-borne organisms survive once in soil.
The state of California has allowed use of untreated graywater for landscape irrigation since 1992, and other authorities have followed suit. Use of greywater on vegetable gardens or fruit trees is best avoided, as a precaution.
Greywater should be used in your garden directly on soil or mulch so that it absorbs rapidly; the best way to accomplish this is to use an irrigation dripline on the surface or buried in the topsoil 3-6 inches below the surface. Greywater should be filtered to remove sediment and particles that could clog dripline holes when this method is used.
A home graywater system can be as simple as a hose branched from the drain line of a washing-machine, to a complete drain-waste-vent plumbing system which is separate from any sewage “blackwater”. By replacing all flush toilets with composting toilets, almost all wastewater from a household can be reused as grey-water.
It must be noted that as home greywater system requires regular maintenance by the homeowner. Filtration and storage tanks need to be cleaned periodically for the system to function efficiently and safely.
When cleaning, eye protection, breathing masks and rubber gloves should worn, in order to protect against possible health risks from decomposing materials, low as they may be.
Alternative soaps and cleaning products which are biodegradable must be used. Laundry detergents containing boron, bleach or softening agents should be avoided, as these substances can build up in the soil and harm plants.