By Warren Tenney
People like the idea of reusing laundry water to irrigate their yards. It’s called a laundry-to-landscape graywater system. Installing a graywater system is part of a growing movement of homeowners eager to reduce their use of potable (drinking) water.
Water draining from your clothes washer, as well as from tubs, showers and bathroom sinks, is called “gray water.” This is not to be confused with “black water,” which drains from toilets, dishwashers and kitchen sinks and carries a risk of viruses, bacteria and pathogens.
There are a number of reasons to install a graywater system. Phoenix Metropolitan area households may use up to 70 percent of their potable water outdoors and a graywater system can help to reduce that volume. Using graywater can save money on your water bill and save your city the energy it takes to remove and treat your water and wastewater. It also can be a mistake unless you do your research. Here are 10 questions to consider before cutting that hole in your laundry room wall.
- How much water does your landscape need? First, understand how much water your grass, plants and trees really need to thrive. Second, stop and learn how to manage your irrigation controller. Third, find and fix leaks in your irrigation system. These steps are so effective at saving outdoor water many cities offer free workshops to help you with each one.
- How much graywater will your laundry produce? Every load of laundry creates from 10 gallons of graywater from a small front loader to 50 gallons from older top loaders. Consider how many loads you do a week and if you can use all that water efficiently. Graywater should only be stored if the tank has a tight cover to restrict access and prevent a habitat for mosquitos and other pests.
- Do you want to grow food with graywater? When it comes to growing food, graywater is suitable only for citrus and nut trees. It should not be used to grow vegetables, fruits and herbs that could come in contact with the water.
- What do you wash? It is unhealthy to use graywater in your yard when you wash diapers, oily rags or clothes stained with chemicals, such as antifreeze or clothes of someone who has an infectious disease.
- Where are you going to use the graywater? Keep graywater a minimum of four feet away from the exterior walls of your home. It can stain and crack the foundation if you drain it close to your home.
- Are you ready to change detergents? It’s important to know what is in your detergent before pouring laundry water onto your plants and into the ground. The University of Arizona and Tucson Water has a guide to detergents (pdf) for graywater systems.
- Will graywater attract your children or pets? It’s not healthy to allow children or dogs to play in graywater.
- Are you ready to ditch your water softener? Water softeners add salt to your water. Desert soils are already salty and that much salt can build up in the soil and kill even sturdy plants.
- How well do you know your plumbing? A laundry-to-landscape system is more complicated than a simple DIY project. It’s also only practical if your laundry facility is next to an exterior wall. Unless you know plumbing, experts recommend you call in a professional to help set up even a simple graywater system. The City of Tempe offers a rebate to residents to help pay for the cost of components needed to install a graywater system.
- Do you know where your graywater goes now? AMWUA member cities recycle all of the wastewater they collect, putting nearly 100 percent to beneficial use. That wastewater is highly treated and reused to cool the Palo Verde Nuclear Generating Station, restore groundwater, store underground for future use, and to irrigate large grassy areas, such as schoolyards, parks and golf courses. Check with your city. It’s likely the water you send to the sewer is put to good use.
The Water Conservation Alliance of Southern Arizona (Water CASA) has a helpful publication about residential graywater use guidelines. The Watershed Management Group has more information about graywater systems in its resource library.
For 46 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.