It is a simple technology. Rain can be captured from rooftops in a simple rain barrel or in a complex cistern system holding many thousand gallons of water.
The revival of rainwater harvesting in the US began in the 1990s, driven by two movements. The US Clean Water Act, first enacted in 1972, created regulations to clean up the rivers and lakes throughout the country. Starting in 1990, the EPA began requiring municipalities to obtain permits to prevent harmful pollutants from being washed or dumped into stormwater before being discharged into waterbodies. Cities were also required to develop stormwater management programs.
These requirements have motivated cities to design programs that educate residents about water conservation and limit the amount of water going into stormwater systems. Examples of programs that cities have created are porous or pervious paving, tree planting, vegetated swales, and rainwater harvesting.
Problems the programs are meant to deal with include deteriorated infrastructure or new development, which put overwhelming stress on a sewer system. Shawn Hatley, president of BRAE Rainwater Technologies, explains that in Philadelphia, a one-tenth inch of rain will cause water polluted by street grime, leaves, and other debris to overflow the sewer system, sending everything to the rivers and riparian areas. This creates problems complying with EPA stormwater discharge regulations.
There are a variety of products and installation services available for residential and commercial rainwater storage systems.
The City of Austin (TX) Water Utility is a pioneer in rainwater harvesting. It began distributing rainwater barrels in 1999 and has reduced peak day demand by over 300,000 gallons. To put that number in perspective, peak daily pumpage in 2009 was 222 million gallons, according to Drema Gross, division manager in the water conservation division. This rainwater harvesting program has also promoted the development of businesses that provide rainwater harvesting products and services in the area.
Lastly, for the general public at large, the drought in various parts of the US, especially in the West, has popularized rainwater harvesting because of its simplicity. Homeowners are able to purchase rainwater barrels and filters from companies through the Internet, attach garden hoses, and create a simple system to water gardens and lawns with rainwater, thereby reducing their water bills.
Before rainwater reuse was popularized in the US, European companies, such as Bord na Móna, had advanced the technology to enable large underground systems to be built for commercial enterprises or large residential complexes. These systems, with tank capacity as large as 30,000 gallons, contain filters and control systems that can provide rainwater for landscaping at these complexes, as well as luxurious backyard landscaped home gardens.
Rainwater harvesting has also been a job creator. Since the 1990s, the rainwater harvesting market has expanded with the creation of many small business, including Aquascape in 1991, BRAE Technologies in 2001, and RainHarvest Systems in 2007, to name just three. Also, well-established plumbing and wastewater companies, such as Jensen Precast, Watertronics, and Bord na Móna have found it easy to expand their product line to provide the equipment and installation services required for commercial rainwater storage systems.
Consistent Regulations Needed
In 1994, the American Rainwater Catchment Systems Association (ARCSA) was founded and now has over 650 members. ARCSA’s goal is to educate and assist local governments, engineers, plumbers, builders, developers, and others who need to install systems that capture rainwater from roofs and parking lots.
As rainwater harvesting technology and projects have expanded, installers have had to deal with local jurisdictions that were confusing it with graywater or reclaimed water, because there were no rules on the books for using rainwater. Public works departments had to modify regulations–many were now having to revive rules that had been removed from the books years ago for cisterns no longer being installed.
ARCSA points out that harvested rainwater is neither of those. It is stormwater that is conveyed from a building roof (or other source such as a parking lot or garden), filtered and stored in a cistern, and, perhaps, disinfected before being used for toilet flushing or landscape irrigation.
UNUM Control Center in completed parking lot. The electrical and hydro control center controls the irrigation system. It contains filters, pressure
sensors, valves, flow sensors, operator interface, and low- and high-voltage wiring.
Graywater, on the other hand, is untreated wastewater that has not come in contact with toilet waste, which is labeled as blackwater. Graywater includes used water from bathtubs, showers, lavatories, and water from clotheswashing machines. It does not include wastewater from kitchen sinks or dishwashers.
Reclaimed water is domestic wastewater treated at the tertiary level by a public agency and is suitable for controlled use such as supplying water closets, urinals, and trap seal primers for floor drains and floor sinks. It is conveyed in purple pipe systems.
Chris Keiger, with Bord na Móna, explains that regulations vary widely across the states, with the stakes rising once rainwater is piped into a building where local or state plumbing codes are enforceable. For both residential and commercial reuse, dual plumbing using purple pipes, pipe labeling, blue die injection into non-potable rainwater, plus filtration and disinfection is often required.
ARCSA has worked to bring some sense to this confusion and to standardize the regulations. It collaborated with the American Society of Plumbing Engineers, to write the Rainwater Catchment Design and Installation Standards, published in late 2009. The standards are intended to be consistent with and complimentary to the requirements of the Uniform Plumbing Code, International Plumbing Code, and National Institute of Health.
The objectives of this standard are to provide guidance on how to create and maintain a healthy alternative to utility-provided water and to optimize rainwater utilization, according to the authors. The authors of the standards argue that rainwater systems are capable of producing high-quality water to levels meeting public utility standards if properly maintained by the system owner or operator.
The main issue is the desire on the part of homeowners to use captured rainwater for clothes washing and toilet flushing, which may conflict with local regulations, according to technical services supervisor Ryan Young, at St. Charles, IL-based Aquascape. Aquascape designs and installs ecosystem ponds that feature rainwater harvesting, For example, Willow Springs, IL, regulators required an enhanced filtration system to guarantee that all bacteria would be eliminated from the water when Aquascape installed an ecosystem pond at a residence.
Rick Reinders, president of Watertronics in Hartland, WI, says future trends and technology development will see increased water reuse for domestic uses. The true costs of potable water will push this development. Purifying rainwater for drinking water is less expensive than desalination and more sustainable, he says, since desalination creates brine, which must be disposed of.
Keiger, a geologist focused on business development and water reuse initiatives with Bord na Móna Environmental Products US, headquartered in Greensboro, NC, agrees. “European countries are way ahead of us in harvesting rainwater. They use water for toilet flushing, clothes washing, and showers, unlike in the US.”
Bord na Móna’s parent company, in Ireland, already had rainwater harvesting products it has been selling to these countries for a number of years, and it was easy to adapt and create a product line for the US in 2009, says Keiger. Sales of rainwater products have more than doubled in the past year, he says.
Cities Seek Solutions
The City of Austin first offered rebates to its residents in 1998 to install rain harvesting equipment, both rain barrels and larger systems. Today, after having given away over 12,000 rain barrels and having redesigned the program twice, customers have reduced peak day water demand by over 300,000 gallons per day.
According to Gross, rebates continue to be offered to customers at $30 per barrel, for up to four barrels. She says people are being encouraged to install larger systems, which have more impact than barrels. Large pressurized systems with tanks and pumps, first flush filters, and concrete pads can earn rebates of up to $500, based on a per-gallon cost calculation. She estimates that 100 customers–both commercial and residential–have installed the large systems.
Around 2003, before she came to the department, Gross says rebates were discontinued and instead, the department purchased rain barrels in bulk from Canada and offered them to customers at reduced prices–around $40 to $60 per barrel–quite a steal compared to today’s prices. It was considered an education program and incredibly popular at a time when not a lot of businesses provided equipment. It also gave the staff opportunities to talk to customers about other water efficient programs.
The distribution program was discontinued in 2008, because the utility did not want to compete with local businesses, which had increased in numbers by then. Furthermore, the utility wanted to stop trucking the barrels from Canada to reduce its carbon footprint.
The water department also offers free irrigation audits and rebates for system upgrades as an incentive to use rainwater for all, or a portion, of a customer’s irrigation.
The current program underwent review this spring in conjunction with its stormwater capture requirements. Staff wanted to simplify the program and go to a per-gallon rebate, making the program more attractive to customers. At the time of the interview in March, Gross says the rebate price was still being debated.
About 50% to 60% of Austin’s water, which comes from the lower Colorado River, is used for irrigation, Gross says. “Anything we can do to offset this is positive for water conservation.” She adds that based on the city’s footprint, “we may have to offset water use using stormwater tanks.”
New Program Starts From Scratch
The City of Los Angeles, CA, created its first rainwater barrel distribution pilot program in July 2009. It was fully subscribed by January 2010. Wing Tam, the assistant division head for watershed protection in the city’s Bureau of Sanitation, says they chose the rain barrel because they wanted to do something simple and practical. He says the target is to start implementing a variation of this program citywide in the fall of 2010, and that results of the pilot project are now undergoing review.
The city’s goal is to reduce polluted water going into the ocean via the stormwater system and to conserve potable water by reducing water now being used for irrigation, Tam says. Thus, the pilot program was concentrated in the western part of the city, considered to be part of the Biona Creek/Santa Monica Bay watershed. The city also received a grant for the pilot from the Santa Monica Bay Restoration Commission.
Los Angeles imports 80% to 90% of its water, and Mayor Antonio Villaraigosa wants to maximize alternative water sources to reduce that percentage.
Tam says, “We want to partner with residents and business to transform rainwater from runoff to a natural commodity … to provide a more sustainable water supply and clean ocean.”
Each of 600 homeowners who signed up for the pilot received a free 55-gallon rain barrel with a screen on top to avoid vector contaminates, such as mosquito larvae. It was installed, by a contractor, next to the home’s downspout, which was modified to drain into the barrels. Each barrel has a spigot at the bottom of the barrel, allowing the homeowner to attach a garden hose or fill a watering can to water landscaping.
An additional 10 planter boxes were installed at business sites. They are typically 3 or 4 feet deep and 10 feet long, and contain native California plantings. The downspout is inserted into the planter, so the water can be filtered, and the plants can absorb the water.
Tam says the department is also offering an alternative service for residents, to help them identify ways to redirect rainwater from a downspout to a rain garden and to help them design the garden. The homeowner would take responsibility for installation. He adds that the department is also promoting large rainwater cisterns with 2,000- to 3,000-gallon capacities in remodeled homes and businesses, but admits these are costly.
In early March, Tam says staff was putting together a report that would recommend taking the program citywide. He was planning to take that report to the Los Angeles City Council for approval by April and is also looking for grants from creative sources to fund the new program.
Tam says one of five options will likely be recommended: extend the current program citywide, distribute free rain barrels and let homeowners install them, provide rebates for rain barrels the homeowner buys and installs, allow homeowners to purchase rain barrels from the city at a discounted price, or work with local installers to incentivise homeowners to buy and install rain barrels.
The Technology Landscape
Rainwater can be stored in many types of barrels and tanks. The type is dependent on the amount of water needed for the end use, whether it is to be installed above or below ground, and factors such as soil type, outside temperature ranges, and cost.
Barrels can be made of wood, fiberglass, polyethylene, concrete, or metal. Wood tanks are popular and are usually constructed of pine, cedar, or cypress, and wrapped with steel tension cables. They are lined with plastic to increase longevity. They vary in size, from small 700-gallon tanks, to very large 37,000-gallon tanks and are usually built onsite by skilled workers.
Galvanized sheet metal tanks are also available in sizes that range from 150 gallons to 2,500 gallons, are lightweight, and easy to move. Most are corrugated galvanized steel dipped in hot zinc to improve corrosion resistance, and should be lined with a food-grade liner, usually polyethylene or PVC.
Fiberglass tanks can be built in capacities ranging from 50 gallons to 15,000 gallons. Polyethylene is the most common and available in most garden supply houses, in capacities from small 50-gallon barrels to large 10,000-gallon tanks. Its best application is above ground. Underground installation will require a special design and reinforcement to withstand soil expansion and contraction. Underground installation also costs more due to excavation and reinforcement costs.
Aquascape’s RainXchange rainwater harvest system, rolled out in 2008, is constructed of Aquablox water matrix tank modules, a lightweight structural catchment system. The modules are made of 85% recycled polypropylene and 15% proprietary selected materials, and can be assembled to any size. The excavation is lined with geotextile and liner before the modules are assembled and covered. Installation is illustrated on the company’s Web site, www.rainxchange.com, under products.
Aquascape’s rain gardens are based on recreating a naturally functioning ecosystem using water circulation, filtration, fish, plants, rocks, and gravel. The underground recirculating system collects and filters rainwater that is integrated into a landscape design. It can also be installed underneath permeable pavers. The RainXchange system is available for both commercial and residential applications.
Concrete tanks are very versatile and can either be poured in place or prefabricated. They can be located under or above ground. Underground concrete tanks are prone to cracking and leaking, but can be easily repaired.
Jensen Precast, headquartered in Sparks, NV, manufactures precast reinforced concrete rainwater collection tanks or cisterns. The company has manufactured precast concrete products for 42 years and added rainwater harvesting products in 2009, in response to California’s drought conditions. The company uses concrete containing up to 30% fly ash, and the reinforcing steel is recycled. Tank capacities range from 750 gallons to 50,000 gallons and are sized, depending on the needs of the residential homeowner or commercial property owner.
Other components of the supply package include Orenco pumps, filters, and Rain Bird control panels. An elevation schematic of a typical rainwater reuse storage and pumping system can be found on the company’s Web site, www.jensenprecast.com/products, under Sewer and Storm Drain/Rain Water Collection Systems.
Homeowners make up 90% of Jensen Precast’s rainwater harvesting business, says Charles Moses, product development manager. Small systems start at about $3,000, and the larger systems can cost as much as $10,000, he says. When the system will pay for itself will depend on water rates and whether the water district offers rebates. The stored rainwater is typically used for lawn, garden, and microfarm irrigation; ponds; fountains; and other non-potable water needs.
Watertronics has been in the water pumping business for over 30 years and added the SkyHarvester rainwater harvesting systems to its product line in October 2008. The system is sold as a package featuring either an above- or below-ground composite water storage tank, pump station, and control panel that monitors and controls the flow of pumped water, harvested water, and replenishment water.
Reinders says the company had been capturing rainwater in surface ponds since the 1980s, but, with the growth of the green building industry, it began to focus on a specific product for rainwater reuse.
Watertronics normally chooses to install tanks made of composite materials such as fiberglass, since they are the most resistant to rust, cracks, and corrosion. Choices of concrete or metal tanks will depend on the site and size requirements. Tank size is determined by analyzing how much rainfall can be captured and the site’s typical water-cycle requirements. The Web sites www.watertronics.com, and www.skyharvester.com describe the company’s products.
Bord na Móna sells both package systems and components, according to Keiger. The tanks in its package system are provided by companies that manufacture them. Residential and decentralized markets continue to be Bord na Móna’s core rainwater business, says Keiger, and it is moving into water reuse in intermediate flow markets. Its Web site is www.bnm-us.com.
RainHarvest Systems is a brick and mortar store in Cumming, GA, and supplies complete systems, filtration systems, pumps and controllers, belowground cistern tanks and rain barrels, and even books and classes. Randy Kauk, president, started the company in 2007, when rainwater harvesting started gathering interest, and few companies supplied all the components, he says.
Kauk says the company now has a 12,000-square-foot warehouse and is looking to build a warehouse and distribution center in California near San Francisco, to serve the flourishing West Coast market. Products may be purchased online at its Web site, www.rainharvest.com. The company also has authorized dealerships and installers and online marketing affiliates.
Three Customer Installations
Cigas Machine Shop Inc. produces and supplies stainless steel plate products in production facilities in Coatsville and Pottstown, PA. Owner Craig Cigas explains that municipal water is problematic in his processing. Common additives such as chlorine, fluorides, and the high mineral content can rapidly degrade expensive consumable parts. Rainwater is inherently pure, so no additional filtration or softening equipment is necessary, he explains. BRAE’s rainwater storage system that collected rainwater runoff from the plant’s rooftop into an aboveground tank made perfect sense, and Cigas couldn’t be happier.
The system was designed with 78,000-gallon storage capacity in three interconnected tanks, first flush diverters, calming inlets, and a rainset control station integrated with metering, backup supply automation, and remote monitoring capabilities. It was commissioned in mid-August 2009.
Initially, Cigas says the system was designed to supply non-potable water for process equipment and sanitary use, but the system was expanded to also include potable use with the addition of a UV filtration system. Since commissioning, the rainwater system has been the sole source of water for the building.
“We sized the system so that 60% of the water supply would support all staff and 24/7 operation of the building for 60 days without rainfall,” says Cigas. That was the worst-case scenario without the impact of the water-saving plumbing fixtures installed throughout the building. He says the area experienced record snowfalls and extended periods with temperatures below freezing. These conditions did not cause problems with the rainwater system.
The system collects less than one third of the runoff from the building’s roof surfaces so if usage increases beyond current capacity, it can be expanded with a second installation.
Cigas says, “We only considered materials and technologies that provided a return on investment of about two years.”
The rainwater system didn’t meet that goal, because municipal water in the area is relatively inexpensive. The cost was about 93 cents per gallon of storage, excluding costs for the filtration system and site preparation. “To justify the installation, we considered less tangible benefits, most importantly, the water quality,” he says.
Hatley says that cost number is reflective of a larger-capacity system with aboveground storage, which is more economical than belowground storage. Excavation costs do increase the price of installation.
McLean Irrigation, in Alexandria, VA, installed a SkyHarvester rainwater management system a year ago at the Kentucky Court Apartments in Washington DC. A very large complex with over 200 units owned by the Washington DC Housing Authority, it features large landscaped areas. Terry Smith, with McLean Irrigation, reports the housing authority is very happy with it. McLean is now installing a second system for the city.
Smith explains that each building in the apartment complex has multiple downspouts, which feed into a stormwater drain pipe. McLean installers cut the 24-inch concrete pipe 2 to 3 feet under ground, and connected it at a 90-degree angle into a 32-foot tank that had been installed 14 feet below ground. Once the tank fills with rainwater, the overflow is redirected to the stormwater pipe and out to the street.
Smith says the rainwater is used for irrigating the landscape surrounding the apartment building. A submersible variable frequency drive pump is located in the tank, and a controller turns it on and off when the water is required for irrigating. During the summer months, the pump can refill the tank with city water once the tank is emptied of rainwater.
Sean Willyerd, with Tennessee Landscape Services in Chattanooga, TN, describes the SkyHarvester system his company installed at UNUM Insurance Corporation’s new headquarters in Chattanooga. UNUM designed the building for LEED certification.
A 20,000-gallon tank was installed under UNUM’s 92,000-square-foot parking lot. The majority of rainwater runs down through drains set in the pavement. Baffle walls on the tank filtrate out oil and dust. Another filtration system removes grit and debris. The Watertronics variable frequency drive pump station matches pump output to irrigation demand to minimize energy consumption. One-half inch of rain will completely fill the tank.
Willyerd explains that it rains all the time in Chattanooga. Irrigation depends on the weather pattern, beginning in May and continuing until the end of September. Early in the spring of 2009, the system used a little city water, but after June, rainwater provided all the irrigation. He notes that the control box was shut down in December, due to the cold weather to avoid its components freezing. Water continued to be drawn into the tank.