Gray water: It doesn't exactly sound like a delicious, refreshing drink for a warm summer day. That's because the term refers to the cloudy, lukewarm water used for purposes like washing dishes, bathing and doing laundry. Gray water is cleaner and safer than black water, which is the water that comes from your toilet, because it doesn't typically contain fecal matter -- thank goodness. And while neither of these should ever be used for drinking water, gray water can have some beneficial uses in your garden.
You can collect gray water from sinks and showers, but the easiest place to get it is from your washing machine. This appliance is equipped with a pump that typically moves used water into the sewer pipe. But with a little creativity you can divert this drainage into your garden. The first thing you'll want to do is install a three-way valve on the end of your washing machine's drainage pipe. This will allow you to choose when you want to capture your gray water or just send it down the sewer. Then you can collect it in a couple of different ways. One is to direct it into a container, much like the rain barrels mentioned earlier. You can drain water from this drum through a hose and use it to irrigate your plants. Another way to use your laundry water is to route it directly into an irrigation system. This will take a little more work as you'll need to dig trenches and lay pipe that can carry the drainage to your plants.
Because laundry water isn't completely sterile or free of contaminants, there are a few precautions you should take when using it to irrigate your garden. Release this drainage only on flat areas where it will quickly soak into the ground; don't run it through a sprinkler or allow it to pool. This will decrease the chance of human or animal contact. When washing your clothes, avoid using bleach, liquid fabric softeners, and soaps that contain sodium or borax; these substances can be harmful to plants. To reduce the negative effects of such impurities, spread your laundry water over a large area and consider alternating gray water and fresh water irrigation. Finally, be aware that about 30 states have laws regulating gray water reuse. Review these policies ahead of time to ensure that your recycling system doesn't violate any rules.