Greywater is the wastewater produced from baths, showers, clothes washers, and lavatory sinks; this is about 50-80% of the household water consumption which goes directly down the drain. Thats a whole lot of free water that could reduce the STRESS on municiple water systems. The wastewater flushed by toilets, kitchen sink, and dishwasher drains, is called blackwater (kitchen sinks and dishwashers can discharge organic wastes into the drains; grease, meat particles, etc which can cause harmful bacteria).
In many situations greywater used as an alternative water resource requires no treatment except for filtration. However, there are commercial greywater systems that do filter, and chlorinate greywater to kill off any potential harmful microbes, although this treatment with chemicals will kill off the many beneficial soil microbes, and as well can be harmful to many plants.
Greywater can clog up valves and other irrigation components (hair, lint and other suspended solids), therefore these should be filtered out. Several filters do exist on the market for such elimination. Or a sand filtering system could be installed, but sand filtering has a limited life span of 2-3 years before the sand must be replaced.
Rain Water Harvesting and Greywater is a very efficient source for landscape irrigation, which also reduces immediate surface water runoff into storm sewers. Although there is a difference; rainwater is very pure and can be used to irrigate garden root vegetables, and above ground vegetables/fruits even if the rainwater is sprayed above the ground. Greywater on the other hand, should only be used as an underground irrigation supply (as long as greywater does not contact edible portions of the plants), but greywater is especially efficient for watering landscaping; flowers, shrubs and trees. Such uses can legally sidestep lawn sprinkling bans
Use of Rainwater and Greywater is a perfect solution for those concerned about green construction and sustainable development.
* Lower fresh water use
Grey water can replace fresh water in many instances, saving money and increasing the effective water supply in regions where irrigation is needed. Residential water use is almost evenly split between indoor and outdoor. All except toilet water could be recycled outdoors, achieving the same result with significantly less water diverted from nature.
* Less strain on septic tank or treatment plant
Grey water use greatly extends the useful life and capacity of septic systems. For municipal treatment systems, decreased wastewater flow means higher treatment effectiveness and lower costs.
* Highly effective purification
Grey water is purified to a spectacularly high degree in the upper, most biologically active region of the soil. This protects the quality of natural surface and ground waters.
* Site unsuitable for a septic tank
For sites with slow soil percolation or other problems, a grey water system can be a partial or complete substitute for a very costly, over-engineered system.
* Less energy and chemical use
Less energy and chemicals are used due to the reduced amount of both freshwater and wastewater that needs pumping and treatment. For those providing their own water or electricity, the advantage of a reduced burden on the infrastructure is felt directly. Also, treating your wastewater in the soil under your own fruit trees definitely encourages you to dump fewer toxic chemicals down the drain.
* Groundwater recharge
Grey water application in excess of plant needs recharges groundwater.
* Plant growth
Grey water enables a landscape to flourish where water may not otherwise be available to support much plant growth.
* Reclamation of otherwise wasted nutrients
Loss of nutrients through wastewater disposal in rivers or oceans is a subtle, but highly significant form of erosion. Reclaiming nutrients in grey water helps to maintain the fertility of the land.
* Increased awareness of and sensitivity to natural cycles
Grey water use yields the satisfaction of taking responsibility for the wise husbandry of an important resource.