Greywater Turned Green

By Maura Yates

Chances are you have heard the term “greywater” but may not be quite sure what it means. Greywater is the water that goes down any drain in your home, excluding your toilet and kitchen sink water. Picture a color scale with white on the left and black on the right: if white represents fresh drinking water and black represents dirty waste water (toilet water or black water), greywater is in the middle because it’s not clean enough to drink, but it certainly isn’t polluted enough to flush down the drain. Because of its unique makeup greywater offers many versatile options for use in outdoor landscaping.
Greywater has a smaller concentration of pollutants than black water, which makes it a good source for irrigating via a simple system that connects your indoor and outdoor greywater sources with your exterior irrigation needs. Anywhere between 50 to 80 percent of residential wastewater is suitable for watering your landscape. As a result, using greywater will noticeably decrease your freshwater consumption and help lower your water bills.  Essentially you are using a resource twice that you paid for once.  Why waste fresh drinking water on irrigating your outdoor plants when they LOVE reused greywater?!
The big thing to know is that you have to be very careful about what you now put down the drain as ‘away’ now constitutes into your yard. If you use a biocompatible soap, which turns itself into fertilizer, you’ll really see your landscape flourish.
Greywater has a lower concentration of nitrogen and harmful pathogens while retaining a healthy amount of compost material that the plants adore. The less harmful pollutants found in greywater decompose faster and therefore stabilize more quickly and reduce the risk of water pollution. However, it is important to be mindful of the products you use in your greywater sources and make sure that they are environmentally friendly because they will be watering your plants once they make their way through the pipes.
Detergents are the most important consideration because they contain chemicals that don’t break down easily and can be harmful to the plant. By changing your detergents, you can decrease the amount of chemical pollution in water.  For more in-depth information in greywater detergents, check out the Rainwater Harvesting for Drylands website.

You will need to consider several variables as you select the type of greywater system that will best fit the needs of your home. But, before you begin this process, take inventory of your greywater sources including the washing machine, bathroom sinks and shower. If you are not sure how much each appliance or fixture uses, check out the chart at the end of this article for an approximation of gallon usage.
Once you have determined the how much greywater your home generates, be sure to check with your local government regarding any special concerns or regulations they may have regarding the placement of a greywater system. In Arizona, if you follow the Department of Environmental Quality guidelines you are not required to get a permit for your greywater system.
For specific designs that suite your needs, use Oasis Designs™ guidelines for selecting your system in the book Create an Oasis with Greywater.
Not only does a greywater system save you money—it helps conserve energy by decreasing the amount of wastewater that needs to be pumped from your house to the treatment plant. The additional bonus is that greywater helps to recharge the groundwater and lessens the strain on your municipal treatment plant or septic system.
Although it may seem daunting at first, using a greywater system will create a thriving landscape AND ease your conscience when you accidentally leave the sink running while you brush your teeth or when you take a relaxing shower that might be a bit longer than planned!