How can you recycle water for your outdoor garden?

Aerial view of a water treatment plant. — Recycling water reduces wastage. Prasit photo / Getty Images

Did you know that landscaping irrigation accounts for about one third of all residential water use in the United States? That means that we dump 7 billion gallons (26.5 billion liters) of clean, drinkable water on our lawns every day [source: EPA]! How can we reduce this amount? By recycling water. Just like recycling aluminum, glass, plastic and paper decreases the amount of trash in our landfills, recycling water reduces the amount of water that drains into our sewer systems. Perhaps the cheapest and easiest way to do this is by collecting used or untreated wastewater from your home and irrigating your outdoor garden with it.

You'd be surprised how much water you can safely divert from the sewer to your garden. One great source is the drainage from your roof. Many houses are already outfitted with gutters that can easily be retrofitted to funnel rainwater into barrels. Here it can be stored until you need to water your plants during drier weather. You can also recycle gray water, which is the drainage from your sinks, showers, laundry, dishwasher and other non-toilet sources. Capturing this water may take a little more effort, but the benefit to the environment and your wallet can make gray water recycling well worth it.

So exactly why should you go to the trouble of recycling your water? For one, it contributes to a healthy environment. Less water is diverted from sensitive ecosystems and into our municipal water supplies and, as a result, less nutrient-rich wastewater is discharged back into these ecosystems. While this may sound like a good thing, the high levels of nutrients found in wastewater can actually be harmful, encouraging algae growth and choking out other aquatic life. Recycling water also saves energy by reducing the need to pump it from rivers, reservoirs or out of the ground, and in some cases, transport it hundreds of miles to meet the demands of arid cities. And if those reasons don't appeal to you, there are some pretty important benefits to you as a water user. Recycled water can help lower your utility bills and is not usually subject to use restrictions during times of drought.

Collecting Rainwater

Do you know how much water rolls off of your roof when it rains? It's probably more than you think. A good estimate is a half a gallon of water per square foot of roof during a one-inch shower. That's 500 gallons (1,893 liters) of water on a 1,000 square foot (92.9 square meter) roof!

You can easily divert this water to your outdoor garden, particularly if your home is equipped with a gutter system. There are just five simple steps:

First, you'll need a big container, known as a rain barrel, to capture water channeled through the downspouts. Fifty-five-gallon (208-liter) food-grade plastic drums work great because they're never used to hold harsh chemicals and they won't rot or rust. The walls should be opaque, as clear or translucent vessels can encourage the growth of algae. Before using your rain barrel, clean the inside with solution of 1/8 cup of bleach and 5 gallons (19 liters) of water.
Next, you'll want to install a spigot. Don't place it at the very bottom of the container where settled debris might clog the flow. Instead, drill a 15/16-inch (2.4-centimeter) hole a few inches above the bottom and thread it with a 3/4-inch (1.9-centimeter) spigot similar to the ones found on the exterior wall of a house.
Now build a platform for the rain barrel. This gives you some clearance to fill watering cans and provides more water pressure to push the water through a hose. Use something strong to construct this foundation, though, as 55 gallons (208 gallons) of water weighs almost 500 pounds (226.8 kilograms). Concrete blocks work nicely.
Once the platform is in place, you can link the downspout to the rain barrel. Mark the downspout a foot or two above the top of the drum as it rests on its elevated foundation. Cut the downspout with a hacksaw or tinsnips and connect it to the container with a flexible plastic pipe known as a downspout extender. The bottom end of this pipe should fit tightly into the barrel to prevent mosquitoes from entering and laying eggs.
Finally, drill a small hole near the top of the container to drain excess water and prevent overflow. You can connect this opening to a hose and divert excess water to your garden or to an additional rain barrel. Place a screen over the hole to keep mosquitoes out.

Recycling Gray Water

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.

Can I Use Gray Water to Irrigate My Veggies?

Because gray water can contain viruses and bacteria, some gardeners are hesitant to use it in their vegetable gardens. If you choose to irrigate this way, use drip hoses at ground level so the water is unlikely to splash onto the edible parts of the plant. If you're growing root crops, it might be best to avoid gray water altogether, especially if they're meant to be eaten raw. While the chances of contamination are low, the only way to be completely safe is to use gray water on grass and ornamental plants only.

Author's Note

The town in Louisiana where I grew up draws all of its water from an underground reservoir known as an aquifer. Unfortunately for local residents, it's not being replenished as fast as it's being used, and the level of the aquifer has dropped dangerously low. The irony of the situation is that the region gets a lot of rain -- about 55 inches (140 centimeters) per year. Imagine the amount of water residents might save by recycling some of this rainwater to irrigate their lawns and gardens!

I don't know about you, but these kinds of simple solutions are exciting to me. I hope by recycling some of your water, you can get a similar sense of personal satisfaction.

Sources

Environmental Protection Agency. "Can Rain Barrels and Gardens Help Keep Sewage in the Sewers?" September 21, 2011. (April 29, 2012) http://www.epa.gov/sciencematters/january2011/rainbarrels.htm
Environmental Protection Agency. "Outdoor Water Use in the United States." February 8, 2012. (May 6, 2012) http://www.epa.gov/watersense/pubs/outdoor.html
Environmental Protection Agency. "Water Recycling and Reuse: The Environmental Benefits." April 4, 2012. (May 6, 2012) http://www.epa.gov/region9/water/recycling/
Environmental Protection Agency. "What Is Green Infrastructure?" March 21, 2012. (April 29, 2012) http://water.epa.gov/infrastructure/greeninfrastructure/gi_what.cfm#rainwaterharvesting
Greywater Action. "About Greywater Reuse." 2012. (April 29, 2012) http://greywateraction.org/greywater-recycling
Greywater Action. "About Rainwater Harvesting." 2012. (April 29, 2012) http://greywateraction.org/content/about-rainwater-harvesting
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New Mexico State University. "Safe Use of Household Gray Water." February 1994. (May 6, 2012) http://aces.nmsu.edu/pubs/_m/m-106.html
Rutgers New Jersey Agricultural Experiment Station. "Rain Barrels." May 7, 2012. (April 29, 2012) http://water.rutgers.edu/Stormwater_Management/rainbarrels.html
Southwest Florida Water Management District. "Recycle the Rain." 2012. (April 29, 2012) http://www.swfwmd.state.fl.us/conservation/rainbarrel/
University of Massachusetts Extension. "Recycling Gray Water for Home Gardens." 2012. (May 6, 2012) http://extension.umass.edu/landscape/fact-sheets/recycling-gray-water-home-gardens