Sarni said that food and beverage companies were some of the first to work with him—he has consulted Coca-Cola on water management issues, for example. Others that are trying to get in front of the water problem include companies such as SABMiller, which has worked with the Nature Conservancy to protect freshwater sources in Latin America.  Governments can also act. Take Singapore: The island nation gets a lot of rain—on average, it rains there 178 days per year. But it's a crowded country, and there is little space to catch and store water, so demand still exceeds supply. Singapore has been successful in implementing water treatment and recycling programs, and water has now become an export business for the country.  Read MoreThe most expensive US cities to buy a beer  Israel has built an industry in desalination to tackle its own water scarcity problems, and it has exported its expertise to California. Both regions have become "water technology hubs" as a result, Sarni said.  Private and public sector institutions face three different types of water-related risk, he said.  First, there are the physical risks of water: The risk that a region may lack sufficient supply, or that the local water supply might be of poor or unstable quality. For example, Sarni noted in one of his reports that a large beer company suffered a loss on the order of $3 million when a drought stopped business in one of its factories in Ghana.  Read MoreCalifornia landowners resist efforts to monitor groundwater  Second, local water regulations or regulatory changes might challenge some companies' ability to do business.  Finally, companies face risks to their reputation—they need to consider how their use of water will be viewed by the communities around them.  "You can quantify the business value at risk from those three dimensions, and that drives companies to develop water stewardship strategies and make investments to manage that risk," Sarni said.
Competition for water is forcing companies and governments to treat water as a more precious resource than they have in the past.