Precious Water: Sustainable Indoor Water Systems

New techniques and technologies--including bathroom and lavatory fixtures--help boost full-building water efficiency
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Sponsored by TOTO and Zurn Engineered Water Solutions
C. C. Sullivan

Water Use, Indoors and Out

By juggling these variables successfully, green building professionals will have any number of opportunities to create sustainable structures, transitively turning their occupants into eco-warriors. In the design or analysis of new construction, it is first useful to look at system-wide water conservation approaches.

Technique
Indoor/Outdoor
Application
Description

Dual plumbing

Indoor Makes use of rainwater, gray water, and recycled or any otherwise non-potable water (for toilet-flushing, or site irrigation)
Recirculating systems Indoor For centralized hot water distribution
Point-of-use water heating systems Indoor For locations more distant from the central hot water (eliminating the high level of embedded energy in delivery of pre-heated water)
Water Budget approach Outdoor Makes use of regional guidelines and data (such as California's Irrigation Management Information System) to schedule irrigation
Micro-irrigation Outdoor For non-turf areas. Eliminates wasteful sprinklers and sprayers.

Outdoors: These techniques can be combined with other outdoor conservation and recapture strategies, such as rainwater harvesting. Other strategies for reducing water use outside the building include separate water meters for the building and the landscaping, and use of state-of-the-art irrigation controllers as well as simple strategies like self-closing nozzles for hoses.

The benefit of such approaches, notes Marty Eberhardt, executive director of the Water Conservation Garden in El Cajon, CA, is that they address the main challenge of system-wide retrofitting. "The greatest challenge to landscaping conservation is landscape retrofits," says Eberhardt. "Because it costs up-front money that people don't want to pay, there can be resistance to swapping out old existing irrigation systems for up-to-date sustainable ones. New construction is easier because landscaping costs are already being discussed." Eberhardt notes that some regions offer rebates for the installation of weather-based irrigation controls, known as WBICs, which can offset system upgrades.

Another challenge is simply the attitudes of building operators. Irrigation strategies are crucial, regardless of whether the buildings are located in areas of severe drought, as was recently the case in the American Southeast.

"Those designing and building current irrigation systems have thus far not embraced sustainable strategies, especially in areas like New England which are mistakenly seen as ‘water-rich,'" says Raymond Jack, Director of Public Works in Falmouth, MA, and president of the Massachusetts Water Works Association. According to Jack, numerous municipalities faced with water shortages are planning outright bans on irrigation of any kind: "A smart long-term strategy for irrigation and landscaping contractors would be to introduce sustainable elements as soon as possible," adds Jack. "Short-term profit shortfalls are a very small price to pay in the face of having one's entire industry banned."

The best way to assess the conservation value of a particular product or system approach is the cost per acre-foot, contends Chris Robbins, Water Conservation Supervisor for San Diego's Water Department. "We want to implement programs that are typically less expensive than the purchase price of raw water," he explains, adding that regional offices such as his offer guidelines for water conservation.

Indoors: Water conservation strategies inside the building should also focus on system-wide challenges. For example, while gray-water systems can reuse supply water for toilet flushing or other non-potable uses, building designs need to ensure the minimum water quality required for all downstream systems. In addition, specific technologies needed for effective solids composting and urine separation are not yet commercially available.

Toilet flushing accounts for the most water consumption in commercial buildings today-as much as 1.2 billion gallons every day. Instead of 1.6-gallon-per-flush valves, water closets are now available with highly effective, 1.28-gpf versions with hands free sensor-operated flush valve and bowl combinations. A large water spot, siphon jet flushing and a fully glazed trapway help ensure adequate carry.

Photo courtesy of Zurn Engineered Water Solutions

Still, bathroom strategies, the primary focus of this continuing education unit, provide one of the best methods for conserving water. In most buildings, toilets consume the most water-usually between 25 percent and 33 percent of the total amount. With a U.S. population of 300 million, one can conservatively estimate that 500 million gallons of water are used each day, just to flush toilets. Now factor in showers, baths, shaving, and hand and face washing: The United States easily uses more than a billion gallons of water daily in its bathrooms. That's the reason toilets were mandated to go from 3 or more gallons per flush to 1.6 gallons per flush (gpf) in the Energy Policy Act of 1992. Even an overall strategy that conserves only an extra one percent of bathroom usage would save more than 10 million gallons of water a day.

The key is to focus on the prudent application of these strategies with appropriate fixtures and fittings that are compatible with the overall system engineering in commercial structures, multi-family residential buildings and high-use facilities, such as airports and arenas. The reason is that poorly employed sustainability strategies can wind up wasting more water than they save, notes Jack: "Many varieties of low-flow toilets have wasted water rather than saving it, because one flush is not enough." Education and awareness of end-user needs and the meanings and long-term effects of fixture specifications help solve such dilemmas.

 

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Originally published in GreenSource
Originally published in January 2008

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