When we are so concerned about the water conservation these days we must take in consideration the benefits of using the Greywater. The best advantage of using greywater, is that it can be used for landscape irrigation. This not only conserves treated tap water, but benefits landscape planting material because it sometimes contains beneficial soil nutrients such as phosphorus and/or nitrogen.
Can we regain the "green" landscape in Las Vegas where for several years now all the efforts were concentrated on replaceing it with dry "deset" landscape?... 
The best advantage of using greywater, is that it can be used for landscape irrigation. This not only conserves treated tap water, but benefits landscape planting material because it sometimes contains beneficial soil nutrients such as phosphorus and/or nitrogen.
What is "greywater"? Greywater is defined as the wastewater produced from baths and showers, clothes washers, and lavatories. The wastewater generated by toilets, kitchen sinks, and dishwashers is called blackwater.
According to the EPA, the average family of four uses 400 gallons of water a day - 146,000 gallons a year. That's a lot of water that quickly runs down the drain! However, much of the water used is clean enough to easily be treated and reused for non-potable (non-human consumption) purposes, such as gardening, flushing toilets, and exterior or clothes washing. Approximately 50% of the water households use annually (73,000 gallons per year) can be recycled and reused. In addition to saving homeowners significant cost in municipal water charges and reducing the demand on freshwater supply, the 73,000 gallons of freshwater saved each year is enough to provide drinking water for more than 300 thirsty people - per year.
It's a waste to irrigate with great quantities of drinking water when plants thrive on used water containing small bits of compost. Unlike a lot of ecological stopgap measures, greywater reuse is a part of the fundamental solution to many ecological problems and will probably remain essentially unchanged in the distant future. The benefits of greywater recycling include:
- Lower fresh water use
- Less strain on failing septic tank or treatment plant
- Greywater treatment in topsoil is highly effective
- Ability to build in areas unsuitable for conventional treatment
- Less energy and chemical use
- Groundwater recharge
- Plant growth
- Reclamation of otherwise wasted nutrients
