Rainwater is an increasingly popular irrigation source
Over the years, I’ve been told by many turf care professionals – including those with the latest in high-tech irrigation systems – that while their irrigation systems are indispensable tools, there’s still no substitute for natural rainfall. With municipal water prices soaring and irrigation restrictions in place in many cities, rainfall is now more valuable than ever. So, maybe it’s not surprising that irrigating with rainfall is becoming a more popular approach.
Even with the marvels of modern science, we still can’t control when and where it rains, or how much. Until scientists give us a way to do so, the best we can do is collect and store rainwater, and then put it where it’s needed. About 15 years ago, inspired by his escalating water bill in Austin, Texas, homeowner Doug Pushard decided to do just that. “I wanted to find a way to water my yard without writing huge checks every month to the water company,” he recalls.
Many people have visions of rain barrels when they hear about irrigating with rainwater, but most systems are constructed on a much larger scale and integrate with existing irrigation systems to properly irrigate turf and landscape plants.
Pushard heard about some early pioneers who were using rainwater to irrigate. However, when he went in search of guidance and products to help him irrigate with rainwater, he found a drought of resources. “I ended up buying a tank and a bunch of different parts and figuring out for myself how to do it,” Pushard explains, “but I thought, ‘This is ridiculous.'”
To help others and promote the idea of using rainwater for a variety of purposes, Pushard founded HarvestH20.com, a website dedicated to “the advancement of sustainable water management practices for individuals, families, communities and businesses.” The website acts as a clearinghouse for news, tips, resources and product information related to conserving water and using rainwater in applications, most notably, landscape irrigation.
As more people have become interested in irrigating with rainwater, product manufacturers have stepped up to serve the market. “Most of the bigger companies, such as XerXes, were actually manufacturing tanks for wastewater or petroleum, and they saw that they could make slight modifications to their tanks and sell them for rainwater harvesting,” Pushard explains. Some product manufacturers from the green roof industry have also ventured into rainwater harvesting. “Charlotte Pipe is now building products for this industry, and John Deere is also moving in, as well,” he adds. “It’s still a pieces and parts market, mostly, though. We’re not to the point where there’s a really good distribution network. People often have to go to an irrigation supplier for pumps and a hardware store and a plumbing store for other components.” Many of those installing rainwater irrigation systems end up ordering over the Internet, where they might be able to find a single source for the various products needed, he says.
Typically, rainwater harvesting for irrigation purposes is accomplished using high-density plastic tanks located near a building roof. From there, a submersible pump feeds the collected water out from the tank and into the irrigation system.
You might be surprised to hear about the need for equipment and technology when it comes to harvesting rainwater. “Many people think it’s just putting a rain barrel out in the yard to collect rain, but you can’t water much turf with a 50-gallon barrel,” says Pushard. On the contrary, true rainwater irrigation systems are just that, systems, and most integrate with existing underground irrigation infrastructure, he adds. All rainwater systems require a tank, typically constructed of drinking water-grade, high-density plastic. In colder climates, or where space is limited, the tanks can be buried. In most cases, however, they are placed aboveground, and often near a house or building to take advantage of the collection capabilities of the roof.
In many cases, depending on local code and other factors, the irrigation system is replumbed to direct water first into the tank. Auto-fill functions can be added to keep the tank filled to a certain level with domestic water in the event there isn’t a great enough supply of rainwater, or the tank can be filled manually with a hose. Submersible pumps with a motor relay valve are often installed in the tank. “Those hook to your irrigation controller,” Pushard explains. “When the irrigation controller comes on, the pump goes on. When the controller goes off, the pump goes off. From there, it’s just plumbed like a normal irrigation system. The only difference is where the supply is coming from.” Oftentimes the permitting process is similar to a traditional irrigation system, he adds.
Pushard says it’s not a big leap to get into rainwater irrigation for someone already accustomed to working with more traditional irrigation systems. “Most people get into it because their customers start asking for these systems,” he explains. “A lot of irrigation people will already know how to do pump sizing. Most irrigation people already know about backflow preventers. [In some localities, a more expensive “high-hazard” backflow preventer may be required, he notes.] The other factor is tank sizing, and there’s a calculator available on our website to help out with tank sizing.”
While still small, the rainwater harvesting industry has grown dramatically in the last decade, says Pushard. “I know people all across the country who are doing it, and it’s become pretty widely accepted,” he explains. In fact, he points out, Australia has mandated the practice, and both Germany and Japan require rainwater harvesting in new developments.
Here in the U.S., different cities have taken various approaches to rainwater harvesting, says Pushard. In Texas, for example, Dallas has a ban on the use of rainwater for irrigation (it’s currently considering lifting that ban), while Austin is offering tax incentives for those who adopt the practice. While for-profit municipal water companies and city plumbing inspectors may be wary of decreased revenues and increased workloads, most cities encourage the practice, he says. The LEED green building program is also driving interest in rainwater harvesting, Pushard points out, explaining that both Gold and Platinum certification in the program awards points for the use of rainwater and irrigation in residential commercial settings. “So more architects are designing these systems in, but then they struggle to find someone who knows how to actually install them,” says Pushard.
In some cases, such as in Seattle’s Green Streets program, rainwater harvesting is promoted not only as a way to conserve water during irrigation, but as a way to capture and utilize stormwater runoff. For property owners, there’s a noticeable reduction in water costs. And, Pushard adds, rainwater also promotes healthier turf by eliminating many of the salts often found in irrigation water. All the way around, it seems, the use of rainwater for irrigation is a common-sense idea that has the potential to grow in the future.
Patrick White is a freelance writer and editor who has covered every aspect of the green industry in the past 13 years. He is based in Middlesex, Vt., and is always on the lookout for unusual stories.