Greywater Turned Green
By Maura Yates
This time of the year I get a lot of questions about how to best water our yards. Short of standing with the hose or installing a sprinkler system, what can we do? Two of my favorite solutions are greywater and rain water harvesting. Over the next few weeks we are going to explore these options, starting with greywater.
For the longest time after I went to my first permaculture class in 1991 I understood the notion of water harvesting to be one where I had to collect and store the water in some kind of container. The part that I missed was that a perfect storage container for the water is FREE… it’s the ground around my home. That’s right, don’t build tanks, put gutters in place to put the water in the ground where you need it. Our articles over the next three weeks will share many strategies about just how to do this.
Chances are you have heard the term “greywater” but never been quite sure what it means. Greywater is all the water in your home that goes down a drain, 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 make-up 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.
Why waste fresh drinking water on irrigating your outdoor plants when they LOVE reused greywater?! Plus, 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, 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.
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. (See document here.)
For specific designs that suite your needs, use Oasis Designs™ guidelines for selecting your system in the article Create an Oasis with Greywater available at this link
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 your 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!
Appliance Water-Use Reference sheet:
United States clothes washing machine (top-loading): 30 gallons per cycle
European (front-loading) clothes washer: 10 gallons per cycle
Dishwasher: 3 – 5 gallons per cycle
Low-flow showerhead (per shower): 3 – 7 gallons per average use
Other sink use (shaving, hand washing, etc.): 1 – 5 gallons per average use
For more in depth information in greywater detergents, check out Rainwater Harvesting for Drylands website at: http://www.harvestingrainwater.com/greywater-harvesting/greywater-and-your-detergent/.
• Greywater is the water that goes down your shower, washer and sink (not including the kitchen.)
• Blackwater, which is not usable in our landscape, is the water that goes down the toilet and kitchen sink.
• Don’t ever store greywater, as it begins to smell very quickly.
• Greywater is legal in some states. Check with your local municipality for the regulations in your area.
• To see Arizona’s regulations click here
We also have two fantastic books on the topic. Create an Oasis with Greywater gives you the inside scoop on irrigating with household wash water while relieving septic tank strain and doing it all chemical free! Plus Rainwater Harvesting for Drylands Vol. 1 shows you how to select, place, size, construct, and plant your chosen water-harvesting “earthworks”.Most of all have fun with your greywater. Have a great green day.