When Gray Equals Green

PICTURE YOURSELF IN A UTOPIAN WORLD. Lush, cool, sparkling water everywhere. Always clear, always clean, always cared for. But most of all—always available and forever flowing.

Now, back to reality. As a nation, we are facing a water crisis. One reason is that our country’s population has gone from 150 million to 300 million within the last century. This growth has created an increase in water demand, taking a toll on our water supply. And instead of finding new resources, we continue to use the same ones we’ve used for decades.

In addition to our population explosion, millions of gallons of clean water are wasted every year. This is largely due to broken pipes, overuse of water or just plain negligence. Changes in our climate have also contributed to our water shortage. At least 36 states are expecting local, regional or statewide shortages by 2013, according to the U.S. Environmental Protection Agency.

However, those in the green industry can help with this water crisis.

Outdoor water use on landscapes accounts for 50 to 70 percent of the total water utilized in households. Therefore, you as a landscape professional can save green—as in plants and money—by reducing the use of potable water while also reducing the impact on already antiquated sewer systems in many cities today. One way to do this is by using gray water.

Think outside the yard for a moment by going into the house. Take a look at the water going down the drains of the sinks, bathtubs, showers and washing machines. This is graywater. It can be used for such tasks as you guessed it—landscape irrigation.

Graywater contains residue from skin and soap, and can be rich in nutrients. It can be beneficial to soil, roots, plants and mulch basins that can contain, cover and purify graywater. Another good thing is that graywater does not require extensive chemical or biological treatment before being used for irrigating landscapes.

Aside from the ecological benefit, graywater can also be economical. “Nothing is more energy efficient than re-using water, and California is just starting to get it,” said Steve Bilson, chairman and CEO of ReWater Systems, Inc., San Diego, California. “Nineteen percent of all energy in California

goes to pumping water around the state. Once that water is used, they would then have to pump more for the sewer system.”

Graywater is not to be confused with blackwater, which is wastewater from toilets, kitchen sinks and dishwashers. Blackwater should never be reused in the home because of possible contamination by bacteria, viruses and other pathogens.

You’re probably wondering how you may retrieve graywater. This is what’s known as graywater reclamation. There are two ways.

One method is bucketing. If you have a pot, pail or bucket, you’re in business. Simply take one of these containers into the shower with you and set it in the stall, allowing your shower water to drop into the container. When finished, take the bucket or pail outside and pour the water onto your plant material. Magic! Another example is to leave the bathroom sink plugged while washing your hands or face. When finished, fill the container with the water. You may also filter your graywater with something as simple as a stocking to trap hair and lint.

A second method of graywater reclamation is diverting. This option might add complexity and cost, but may make graywater distribution easier.

An electrical three-way valve, or in some areas, a manual valve, can be installed into the drainage system of a shower, sink or washing machine. Instead of going to the sewer, the water can be diverted into an alternate drainage. The graywater can then be transported to a surge tank, where it will be filtered and pumped out for irrigation. A passive system utilizing gravity feed can be used where the topography is favorable.

Although surge tanks are commonly used for graywater systems, some experts who use graywater for irrigation do not recommend storing graywater at all. Many states have limits as to the size of the storage tank and how long the water can remain in the tank, depending upon the tier of graywater permit required.

Evan Marks, executive director of The Ecology Center, Berkeley, California, is currently working on a new system in which all graywater in a home can come into a central tank and immediately gets pumped out for irrigation. “If you store graywater for more than 12 hours, it turns into blackwater,” said Marks. “It’s all about designing systems that use graywater immediately.”

Some experts recommend a drip irrigation system for distributing graywater throughout landscapes. “Studies have shown that drip systems are at least 30 percent and up to 60 percent more effective than sprinklers, “said Bilson. “That’s a huge difference, considering a huge amount of all water used in states such as California goes to landscape irrigation.”

Graywater systems have been established in some urban areas since the 1960s. However, they have not been widely accepted in many areas until this past decade. For the majority of the world, there have been strict regulations on graywater that have deterred people from using it. (There are still some states within the U.S. that do not allow legal graywater systems.) Because graywater may contain food particles, detergent, soap residue and possibly some human pathogens, it can often be seen as a public health concern rather than water conservation. Yet, there are no known documented cases showing graywater as a health threat.

While many states have recently adopted policies promoting graywater systems as a result of the water crisis, some state’s regulations have made the use of graywater expensive and time consuming.

Oregon residents, for example, must go through a lot of red tape in order to tap into graywater. Indoor use has to meet strict standards of the state plumbing code, making installation pricey. As it is, plumbing systems that are compatible with mass-produced graywater are hard to find.

Outdoor use of graywater has recently become legal; however, Oregon’s Department of Environmental Quality (DEQ) now has to develop a ‘permit program,’ which is not expected to be finished until late 2011. Until then, Oregon residents must refrain from outdoor use.

In Utah, residents may not be given permits to use graywater until their system has been approved by the state health department. This process can take months.

Arizona has long been considered a model for graywater usage. Since 2001, Arizona residents have had an implied permit to use up to 400 gallons of graywater a day. Those owning their own homes do not need a permit. In an arid state such as this, graywater comes in handy for watering. Mark Shaffer, of the Arizona Department of Environmental Quality, said graywater use quickly picked up steam as water prices have shot up, especially in Tucson.

“Traditionally, Arizona has had one of the most liberal uses of graywater,” said Shaffer. “Because we have a high evaporation rate, graywater gets absorbed into the soil rather quickly here. In other states with higher humidity, graywater could add to an already existing vector and mosquito problem.”

Graywater use in Arizona is now considered mainstream. The state offers tax credits for graywater construction projects and plumbing systems. As a result of pressure from graywater advocates, California recently passed a bill modifying their current standards on graywater systems. Homeowners can now build simple graywater systems for their household use without obtaining a permit.

“In California, you don’t need to have a percolation or soil report if you’re using graywater for drip irrigation only,” said Bilson. “This assumes that the water is being applied uniformly across the property and not being disposed of.”

In some areas, such as Palo Alto, California, the cost for graywater systems could be as much as $5,000. Despite that cost, many residents in this city are willing to pay these prices to help conserve the environment.

“Graywater has been with us for a long time, and there are many people out there that just want to do what’s right by protecting the environment,” said Bilson.

There are some simple guidelines for graywater use that landscape professionals should follow:

It is best to use graywater on ornamental plants and lawns, or to irrigate trees. Graywater should not be used for dust control, cooling, spray irrigation, or any other use that would result in air-borne droplets or mist. Never allow graywater to pond because it can increase health risks and provide breeding grounds for mosquitoes.

As the national water crisis continues to rise, so do the prices for potable water. “There’s not a day that goes by where someone isn’t raising their water and sewage rates 20 to 30%,” said Shaffer.

“More and more people want to find out how to integrate graywater technology,” said Marks. “I foresee, in five years, there will be countless cities making a conscientious effort toward graywater use, and it will be more widely available.”