Where will the future water for our landscapes come from?


By: Warren Gorowitz, CLIA, Ewing Irrigation

It’s no secret that many areas throughout the country are experiencing water supply challenges, or will be at some point in the near future. According to the United States Environmental Protection Agency (EPA), at least 36 states are anticipating local, regional or statewide water shortages by 2013, even under non-drought conditions. This stress to America’s water infrastructure can be caused by budget cuts, growing populations or even extreme weather events that have made water supply planning more difficult.

Where does the landscaping industry come into play with this? Studies show that over 50% of the water used for a typical residential landscape is wasted, often times due to improper water management, causing runoff. The value of water will continue to increase as pricing signals are put into place, such as tiered water rates that penalize high water users and reward those who stay under their water budget.

As an industry, it’s time for us to look for alternative water sources to irrigate the landscape. I predict that within the next decade, many parts of the country may ban potable water use for landscape irrigation. This shouldn’t mean the end of landscaping as we know it, but instead a challenge to our industry to use our water more efficiently and find other sources.

Alternative water sources could include rainwater harvesting. With one inch of rainfall, a 1,000 sq. ft. rooftop can yield approximately 620 gal. of usable water for capture and storage. This water can be stored in above ground tanks or underground cisterns, and then tied into the irrigation system to supplement the potable water supply for the landscape. In addition to serving as an alternative water source for irrigating, this practice can be beneficial in reducing the stress on the sewer systems that may not be able to handle the excessive run-off that occurs during rain events.

There are lots of options for rainwater harvesting, as well as key areas of consideration, such as of anticipated water volume, overflow drainage, etc., that should be carefully calculated before deciding on a specific solution. In its simplest form, this might consist of a 60-gallon rain barrel that captures the water from a downspout on a residential roof, and is then used to hand water a flower bed nearby with a garden hose.

More extensive systems for commercial applications can store thousands of gallons of water, and can be tied directly into the irrigation system with a booster pump to supplement the potable water supply. In areas that receive considerably low rainfall during the summer, which is usually when the landscape has the highest evapotranspiration rate (ET) and needs the most water, the return on the investment for installing rainwater harvesting may be longer than some people are willing to consider.

One challenge that warrants attention with rainwater harvesting is the fact that in some areas and states, water that would ordinarily run off into the sewer system or potentially into the ground water supply, may be counted on for use by someone else downstream. It is important to understand your local laws and regulations regarding the capture and storage of rainwater.
Condensate recovery, or the collection of liquid vapor, is another source of water that can be stored and applied to a landscape when needed. On a commercial application, a 10-ton HVAC unit in the Southeastern U.S. can provide approximately 30,000 gallons of water annually. Water quality issues can be of concern in this application, so it’s important to test the condensate before using it on the landscape.

Similarly, greywater is being brought up more frequently in discussions about alternative water sources. Greywater is wastewater drained from lavatories, showers, bathtubs, washing machines and sinks not used for the disposal of hazardous, toxic ingredients or waste from food preparation. In a residential application, the systems are pretty straightforward and simple. One thing to keep in mind is that you need to check your local laws and regulations to see what guidelines or restrictions for greywater are applicable to your area. In most areas, you’re not able to store greywater for future use without treating it for contaminants, so most of the time greywater is being applied to the landscape as it’s coming from the source.

These are just a few of the many options to consider when looking for alternative sources of water for use in irrigating a landscape. The bottom line: The use of alternative water sources is an issue that will continue to gain momentum in our industry, and one that I encourage all Green Industry professionals to investigate more thoroughly as you contemplate your business strategy in the next few years.

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