When it comes to debate about the environment, global warming has long occupied center stage. People throughout the world are recognizing the need to reduce carbon emissions and to use less energy. But, they may be ignoring another important natural resource: water.

“People have focused on energy efficiency because it hits them in the pocketbook a lot harder than water,” says Greg Steiner, president of GreenLife Guru, a Los Angeles-based consulting firm that helps commercial property owners go green. “But that will change; one day, water will be more precious than oil.”

How quickly that day comes depends on how effectively people respond to Steiner's warning. In the meantime, water is increasingly becoming a scarce commodity due to the huge surge in global population as well as irresponsible and excessive consumption. Today, more than half of the United States is experiencing drought conditions, while other parts of the world face worse or similar situations. As a result, the cost of water is increasing; in fact, it's rising faster than the cost of energy—although you'd never know it given how often people complain about their electricity and gas bills as opposed to the price of water.

In some parts of the country, states and cities have enacted laws to conserve water or to reduce water consumption, and multifamily developers and owners across the nation are implementing water reduction strategies and technologies in their projects. These efforts are good not only for the environment but also for the bank account.

From low-flow toilets and faucets to cisterns that collect rainwater for use in landscape irrigation, there are plenty of opportunities to conserve water both inside and outside of the property. Landscapes, in particular, are water gluttons—they account for 58 percent of all urban water usage. But, they are routinely over-watered by 30 percent to as much as 300 percent.

Multifamily developers and owners have long fought back against the waste. In 2000, Alexandria, Va.-based AvalonBay Communities partnered with Solana Beach, Calif.-based Water2Save to launch a water conservation program at the REIT's California properties. The systems AvalonBay installed tracked and monitored irrigation settings and schedules; eight years later, the savings continue to pile up, and the company has seen a reduction of 39 percent in its outdoor water bills.

But today's holistic water strategies must encompass far more than water conservation. “People are starting to pay more attention to how water is used, where it comes from, and where it goes,” says Frank Sherman, a vice president with Rockaway, N.J.-based Mackenzie Keck Construction who specializes in green building and sustainability.

It's not just about reducing water consumption; it's also about protecting water from contaminants and finding ways to prevent additional stress on cities' stormwater and sewer systems. New York City-based Sheldrake Organization, for example, installed treatment systems in Riverhouse, One Rockefeller Park, for both black water—wastewater from toilets, kitchen sinks, and dish waters—and gray water—from showers and bathtubs, bathroom sinks, and washing machines.

The Riverhouse 32-story, 264-unit luxury condo building, which overlooks the Hudson River and fronts Rockefeller Park, is one of the first multifamily buildings to be certified LEED Platinum. It's black water system takes waste from the building, cleans it, and pumps it into the NYC sewer system; while the gray water system pipes water to the basement where it is treated and used to irrigate the planted rooftop, courtyard, and landscaping around the building.