Watch the video on Greywater Reuse.
Greywater reuse refers to collecting, filtering, storing, and reusing household water that drains from bathtubs, showers, bathroom sinks, and washing machines. Greywater contains a minimum amount of contamination and can safely be reused for subsurface irrigation of lawns, flowers, trees, and shrubs, but it should not be used to irrigate vegetable gardens.
Greywater should not be confused with reclaimed, treated wastewater, which can be used for applications not permitted with untreated greywater, such as toilet flushing and aboveground irrigation. Also, greywater should not be confused with blackwater, which drains from toilets, kitchen sinks, and dishwashers. Blackwater cannot be reused safely because it has high concentrations of organic waste. Similarly, garden and greenhouse sinks, water softener backflush, floor drains, and swimming pool water should not be included with greywater reuse.
Advantages and drawbacks
The most obvious advantage of greywater reuse for irrigation is that it can replace potable water, saving the homeowner money. Also, using greywater may actually be more beneficial to plants than potable water because greywater often contains nutrients such as nitrogen or phosphorus. When irrigating with greywater, however, it is important to control what cleaning and washing chemicals are used in the water so as not to damage the plants. Avoid powdered detergents because they tend to be high in sodium and salts; avoid boron because it can be toxic to some plants; and avoid chlorine bleach, caustic drain cleaners, petroleum distillates, and other chemicals that have unknown effects on plants.
In addition to homeowner benefits, greywater use can reduce the pressure on limited potable water resources in some communities. It may offer financial savings to overburdened sewage treatment facilities by diminishing sewer flows and thereby lessening the need to expand these facilities. Increased greywater use may have some downsides, however: diminished sewer flows mean less water to carry waste to the treatment plant. Also, less water will be available for treatment, resulting in less reclaimed water for municipal and other uses.
Finally, separating greywater from blackwater and reusing it isn't allowed in many areas; therefore, be sure to check local building codes before moving ahead with a greywater reuse system. For new construction in areas that currently prohibit greywater reuse, it's relatively simple to install the home's plumbing so that a greywater reuse system may be added later.
System components and maintenance
If you're planning to collect and reuse greywater, run the drain lines for the bathroom sinks, tubs, showers, and the washing machine to a centrally located holding tank with a filter. Crawlspaces and basements are an ideal location for the holding tank. Water can remain in the holding tank for up to 24 hours. Do not store greywater in the tank for extended periods because the decomposing organic matter in the water will begin to smell foul. From the tank, water can drain or be pumped directly into the subsurface irrigation lines. Locate the irrigation lines about 9 to 12 inches below the ground surface. This is the biologically active portion of the soil and is optimal for breaking down the greywater's organic matter.
It's important to include an overflow valve in the greywater collection system that feeds water directly into the sewer line in case the filter clogs. In addition, include a controllable valve to redirect greywater into the sewer line in case the areas being irrigated become too wet. Regarding the filter, it should be easily accessible and easy to clean. Improper filter maintenance may make the water unsuitable for reuse.
Finally, regular maintenance is necessary to keep a greywater reuse system operating safely and effectively. A basic maintenance plan should include: inspecting the system for leaks and blockages; cleaning and replacing the filter as recommended; flushing the entire system periodically; and regularly inspecting the irrigated areas to make sure that the amount of water being pumped in is sufficient.
To learn more about greywater reuse, visit:
www.ext.colostate.edu/pubs/natres/06702.html
toolbase.org/Technology-Inventory/Sitework/greywater-reuse
www1.eere.energy.gov/femp/pdfs/29267-6.6.pdf
www.oasisdesign.net/
| 
