Water scarcity is potentially one of the biggest problems facing humanity in the next several decades.

Communities and countries around the world already face shortages, some of them severe. Governments are tasked with the challenge of ensuring access to water for their citizens. Institutions such as the United Nations consider access to clean water a human right, for example.

But access to water is also a problem for businesses, which may find themselves in ever greater competition for a finite resource as growing populations increasingly drain reservoirs and rivers.

Companies and investors are taking action to hedge against the business risks associated with water scarcity and spur investments in new technologies.

Some available approaches, such as desalination and water recycling, show promise. But desalination has been criticized for its historically intensive energy requirements and for potential effects on the environment. And water recycled from the bathroom to the kitchen sink, though safe, conjures deeply unpalatable images for many would-be consumers. Billionaire and philanthropist Bill Gates famously drank a glass of water made from specially processed sewage to convince detractors that the water is as safe and tasty as any from a branded bottle.

There are myriad ways to invest in water, including investment funds; start-ups that are developing new technologies, from extraction to metering and management; and global corporations taking water scarcity seriously.

The important thing to remember is just how vital water is for virtually every aspect of human existence and activity, said Will Sarni, a consultant and entrepreneur who specializes in water.

"There is increasing demand for this finite resource and this finite resource is essential to life, but also to economic development and business growth," Sarni said. "You can't generate thermo-electric power without water. You can't grow crops. You can't have manufacturing."