But even so, say experts, the problem is perhaps more an issue of recognizing water's true value, using it efficiently and planning for the lean times, than it is a lack of overall supply.
The ongoing historic American drought, with its cascade effect on food and utility prices at home and food costs abroad, is an example of scarcity's effect.
But superstorm Sandy's deluge and flooding, says Geoff Dabelko, an environmental expert at Ohio University in Athens, is an example of how the term "global water crisis" can be misleading. It tends to imply that there's just one kind of crisis – a water shortage.
"The kind of dead-cow-carcass-in-the-desert image that global 'water crisis' evokes is very real for some people," Professor Dabelko says. "But there are so many dimensions." Too much water – whether from flooding, sea level rise, or more extreme storms – can be just as deadly as too little.
While the balance between water supplies and the demands of a burgeoning population are further complicated by the effect of climate change on delicate hydrological margins, there are those who say there is enough water, if nations learn to plan for a different future – one in which past abundance is no guide.
The growing thirst for water
Water is a part of everything we do: It feeds crops, powers cities, cools computer servers, and is key to the manufacturing of everything from clothes to cars. The billion more people expected on the planet by 2025 will increase water demand for all of those functions. And just to feed those people, water withdrawals for agriculture are expected to increase by about half.
But it's not only about the additional mouths to feed; it's also the growth of new appetites. Much of the growth in demand will emerge from the swelling sprawl of bustling, slum-pocked metropolises across the developing world. For the first time in history, the share of the global population living in cities recently surpassed 50 percent – on its way to 75 percent expected by 2050.