Water scarcity is poised to become one of the biggest issues facing the United States and the developing world in the coming century, according to a panel of water experts speaking the Global Conference. (Full video available here.)

David Beckman of the NRDC predicts that one-third of the 1,000 counties in the U.S. will be at high or extreme water risk by 2050. "It's not just the West," he said.

California is at the center of the water shortage problem in the U.S. Twenty percent of the energy used in California is for water transport, said Evan Lovell, founding partner of Virgin Green Fund. That's because 75 percent of the population of lives in the southern half of the state, while 75 percent of the water is located in the northern half, added Susan Leal of AECOM. Water, of course, is heavy and costly to transport.

UC Irvine Professor Jay Famiglietti said satellite evidence of water depletion in California's Central Valley is "clear and undeniable." Climate researchers predict the snow pack may decrease by 90 percent by the end of the century, which means less groundwater replenishment. Aquifers could dry up within 60 to 100 years, but no one knows for sure because no one actually knows how much water is in the major aquifers of the world. "That's frightening," he said.

Part of the problem, Lovell said, is that water is not priced like food and gas. Many people think of water as a "god-given right" that should be free. Right now, it costs only a third of a penny per gallon, Beckman said.

The enormous water footprint in the U.S. also has a lot to do with our diet, Leal said. For instance, 58 million gallons of water are used to produce eight ounces of milk, and it takes 634 gallons of water to produce the eight ounces of beef for a single hamburger. As developing countries consume more meat, the water problem becomes larger. China has doubled its meat consumption the past two decades. "Water use increases as affluence increases," Leal said.

There are solutions, however. With readily available technologies, "farmers could double production and cut water use in half," Leal said. "There is an opportunity for making investments that will make an impact and make money." Without economic or government incentives, however, most farmers aren't adopting the technologies that are available.

Potable water should also be reserved for when it's needed, Leal added. "There's no reason to be watering a golf course with pristine water," she said. Local governments can have a huge impact. Cities that implement green infrastructure such as rain gardens and cisterns that capture water also "create enough water to supply half the city's needs," Beckman said.

Green infrastructure also helps solve problems created by storm surges that are becoming a regular occurrence in places such as New York, Leal said. Those surges cause "pretty nasty" sewer overflows into harbors and people's basements. Green roofs and green infrastructure not only look nice, but they also help slow those sewer overflows.

Marc Nathanson, chairman of Falcon Waterfree Technologies, said his company's waterless urinals can help solve the scarcity problem, but people need to become more aware of government incentives. The Los Angeles Department of Water and Power, for instance, provides rebates to companies, schools, stadiums and others wanting to install waterless urinals. Each urinal saves 40,000 gallons of fresh water per year, he said.

Even so, his company has been in business for nine years and still hasn't seen a return on investment. "It's a consciousness issue," he said. "It is not a quick fix."

Government regulation of water is a confusing patchwork that's difficult to navigate, Nathanson added. Many of the rules defy logic. For instance, the EPA gives a WaterSense label to products that save water, but his company's waterless urinals don't qualify as saving water because they use no water at all, he said.

Famiglietti and Beckman agreed that fragmented water management in the U.S. makes things challenging. Twenty federal agencies deal with water, in addition to hundreds of state, county and local entities. "We need a national water management commission," Beckman said.

As far as consumer trends are concerned, there's a backlash against bottled water and a trend away from tap water, Lovell said. That provides a growth opportunity for his portfolio company Quench, which is in the bottleless water cooler business.