- Jan 02, 2014
Payback Issues Aside, Rainwater Harvesting Systems Can Really Collect
By Brad Berton, Contributing Writer
Notwithstanding numerous general and site-specific challenges, forward-looking commercial property executives continue green-lighting newfangled rainwater harvesting systems at widely varying sites across the country. And why not, given the ultimately attractive price of captured rainwater?
Precipitation falling on commercial rooftops from the heavens is pretty much free, although there are lingering legal issues over collecting it from parking lots. And even the costs of collection and filtration are less than paying for potable utility water that ends up being used for irrigating landscaping and flushing toilets and urinals.
In fact, the American Water Works Association estimates that non-potable uses account for 80 percent of a typical commercial building’s water consumption, offering even more uses for collected rainwater.
Furthermore, in diverting rainwater that would otherwise end up in stormwater and sewer systems, modern “catchment” systems can likewise reduce corresponding municipal fees—or in a growing number of jurisdictions, even generate related financial incentives. And then there are the related environmental benefits of reducing the amount of potable water utilities need to treat and the runoff flowing into storm drains.
Unfortunately, despite the compelling justifications for investing in rainwater harvesting systems—including innovations reducing maintenance costs—pure payback economics for the most part is not necessarily one of them. At least, not yet.
Despite the impressive roster of systems installed at an array of new and existing commercial projects, other daunting impediments continue to hinder wider adoption of these relatively inexpensive and simple mechanisms. Perhaps the most formidable are the hodge-podge of building and plumbing code treatments of the systems around the country.
Also not to be discounted is a lack of understanding about their considerable benefits, lamented longtime harvesting advocate David Crawford. “You can’t make enlightened decisions if you’re not informed,” stressed Crawford, founder of Salem, Va.-based Rainwater Management Solutions, which has supplied many commercial clients, including providing dozens of rooftop installations at Home Depot mega-stores around the country. He was also recently re-elected president of the American Rainwater Catchment Systems Association, which is working to resolve the awareness issue.
As for the “unpredictable permitting pathways” stemming from inconsistent codes and related regulations, “they mean longer timelines and unknown outcomes—both typically leading to additional costs for commercial projects,” added water systems designer Colleen Mitchell. Based in Washington state, where permitting is smooth for residential RWH systems but still touch-and-go for large-scale projects, Mitchell is a project manager at sustainability specialist 2020 Engineering.
But Mitchell and Crawford remain encouraged that most issues impeding installations will be resolved to a great degree within the reasonably near future. Even the lengthy, often hard-to-project payback periods seem bound to compress as RWH systems become cheaper and more efficient with design and technological advances—and as municipal water becomes more expensive and is increasingly treated as a precious resource. Reflecting wide variations in sites and configurations, system designs and functions, local climate conditions and water/sewer rates (and incentives), payback periods for harvesting systems at commercial properties might range anywhere from 18 months to 18 years or more, Crawford related.
Crawford is confident utility pricing will come to reflect actual potable water delivery costs rather than prevailing subsidized rates. “When we stop giving water away, we’ll start treating it more like liquid gold.”
In fact, there is considerable evidence the nation is already moving in that direction. To wit, the Circle of Blue water news service reports that water prices in 30 major U.S. cities continue to appreciate well beyond general inflation. They rose another 6.7 percent in 2012, and that was actually off a bit from recent years.
Given the nation’s obsolete and crumbling urban sewer systems, chances are more cities will opt to provide incentives to property owners for reducing runoff and discharges, which would bode well for RWH.
Meanwhile, recent technological advances—such as more effective pre-storage filtration and floating-intake mechanisms—are already helping reduce costs of operating and maintaining the systems. For instance, today’s stainless steel pre-storage filter inserts can arguably render the traditional annual or semi-annual cleaning of storage tanks and cisterns unnecessary. Property owners tapping these pre-filtration technologies typically “won’t have to ever empty or clean the tanks for the life of the system,” Crawford contended. “That’s a huge savings.”
The reason is that filters equipped with these advanced inserts keep organic debris out of tanks, allowing formation of a permanent biofilm layer on tank surfaces. This layer—composed of living organisms—also helps maintain water quality by releasing oxygen.
Meanwhile, floating filters draw water from a “clear zone” six to 12 inches below the tank/cistern surface, reducing post-storage debris (and in turn clogs) and the overall filter count.
Some significant regulatory relief—or at least further code streamlining—also appears to be on the way. ARCSA collaborated with the American Society of Plumbing Engineers and other key parties in developing a Rainwater Collection System Design and Installation standard approved in late November by the American National Standards Institute.
The expectation is that a vast number of U.S. and Canadian code jurisdictions will incorporate much of the standard’s particulars, presumably providing some much-needed regulatory consistency. “That means our systems are recognized as a real entity for water catchment and reuse and not just an experiment,” observed another veteran RWH specialist, ARSCA executive director Heather Kinkade, who is based in Phoenix.
As for fundamental RWH functions and required expenditures, system costs, like payback periods, can vary widely at commercial properties depending on site and structure configurations, local climate conditions and other factors. Most installations involve the same basic components—big storage cisterns plus inlets, valves, pumps, filters, pipes, switches and the like—but “we come across different circumstances at every commercial site,” Crawford noted.
Nevertheless, while installing a high-performing system at an existing high-rise might run to six digits, RMS’s average for commercial installations is roughly $25,000, Crawford specified. For a basic system, it is probably reasonable to expect installation costs to range from $2 to $5 per gallon of harvesting capacity, added Mitchell, with capacity depending on a site’s water needs and roof and surface collection areas.
Sourcing one or more large cisterns (and burying them, in many cases) represents a major cost component of RWH systems at commercial properties. Indeed, storage-capacity requirements generally represent the single biggest variable affecting costs from project to project, Kinkade related. No doubt subterranean storage entails additional costs—which in turn depend on site-specific soil and rock conditions affecting excavation endeavors, she added.
Some conservation-minded owners and operators have looked to creatively reduce this component of first costs by repurposing obsolete mega-containers. For instance, Rio Perla Properties is using old beer vats at the redeveloped former Full Goods brewery warehouse in San Antonio, and PCC Natural Markets is using a former sugar storage tank at its store in Edmonds, Wash.
Predictably, certain residue- or contaminants-challenged roofing materials do not make for effective rainwater collection surfaces. These include wood shakes, asphalt compositions and pretty much anything heavily treated with fungicides or herbicides. Copper is generally a no-no, but a 50-year roof made of other metals is probably about as effective for collecting rainwater as it gets, Crawford explained. Popular materials such as clay, slate and membrane materials can all work well, and the “slick” surfaces comprising modern photovoltaic arrays only enhance collection efficiency, he added.
While key variables such as property configurations and local rainfall levels help determine a given system’s functional capabilities, the experts cite one simple mathematical formula to keep in mind: One inch of rainfall captured optimally factors to approximately 620 gallons per 1,000 square feet of roof area.
And as Crawford pointed out, while decision-makers will generally need a permit to collect rainwater that reaches the earth’s surface—such as parking lots—what lands on roofs is typically there for the taking.
Owners and users well beyond the big-box set (which includes Walmart/Sam’s Club and Lowe’s in addition to Home Depot) are embracing the benefits of RWH. These include new corporate offices housing the likes of PNC Financial in Pittsburgh and TD Ameritrade in Omaha. And Swire Properties is integrating a multiple-cistern RWH network into the newfangled “climate ribbon” running through its $1 billion Brickell City Center mixed-use development in Miami.
Even industrial projects large and small are tapping into free rainwater, including locally based Webb Development at its Solon Industrial Park in Houston. Currently in pre-leasing, the project’s RWH system will go beyond landscaping to supplement Solon’s graywater system, which taps HVAC condensate for use in toilets and urinals.
Affordable-housing developer NorSouth Cos. incorporated an RWH system into its Hearthside Brookleigh project in DeKalb County north of Atlanta. And hotels such as the Hampton Inn & Suites Miami Brickell-Downtown are tapping them to help with heavy laundry water needs.
As that last example illustrates, harvesting system designers are increasingly aiming to direct rainwater to additional uses beyond irrigation and toilet/urinal flushing: HVAC cooling towers and fire-suppression systems are two possibilities. As Mitchell put it: “Oftentimes, cisterns are designed with multiple uses in mind.” And Crawford is quick to point out that rainwater in fact is “softer” and hence more effective with laundry washing than treated tap water.
Many, in fact, expect captured rainwater to eventually be purified for potable uses, although regulations will need to be modernized to permit drinking, cooking and bathing. In fact, technology is not the issue here. Rainwater collected from rooftops is typically less contaminated—and hence easier to purify—than the groundwater utilities tap and treat, related Crawford, whose company has installed numerous potable catchment systems. Just run captured water through five-micron filters, then carbon or charcoal filters and on through ultraviolet light, and it is pretty much ready to drink, he elaborated.
He even envisions a day when a Home Depot could bottle up the water it collects from roofs and sell it in its stores. Mitchell likewise envisions potable harvested rainwater before long. “I think that it is a logical next step, and the discussion is occurring at the local, state and federal levels right now.”
Meanwhile, as states and municipalities adjust codes and recognize how RWH systems can benefit water and sewer systems, water-conscious developers should benefit from enlightened policies. For instance, if certain water fixtures can be served entirely with captured rainwater without requiring any utility back-up, officials may be willing to significantly reduce a project’s system development charges and ongoing hook-up fees, Mitchell noted.
Such was the case with 2020’s client, the local group operating as Diluvian L.L.C. that developed the mixed-use Pike Station in Seattle. The RWH system reduced the expected need for potable municipal water, allowing a 1.5-inch connection rather than 2 inches.
“This resulted in over $35,000 in savings,” Mitchell related, “which paid for the rainwater system before it was even installed.”
This article appeared in the January issue of Commercial Property Executive magazine.