Food, energy, and water. They’re all critical to human life, and they’re deeply interlinked. Of the three, water has tended to get the least attention. But that is changing. Fierce droughts in parts of the U.S. and elsewhere, depletion of groundwater, and other factors—including the country’s love affair with fracking—increasingly will highlight the urgent need to ensure adequate water supplies. This means well-situated water-related investments are potential long-term dynamos.

U.S. water infrastructure is in alarming decline. Nonpartisan organizations including the Congressional Budget Office and American Society of Civil Engineers say the gap between what we need to spend to maintain our water infrastructure and what we are spending likely will exceed $200 billion this decade (2011-20) and reach $1 trillion next decade.

Subpar water infrastructure hurts the economy in many ways. It costs an estimated 400,000 jobs a year and lowers per capita disposable personal income by an average of $200 a year. During this decade’s second half, it likely will chop more than a half trillion dollars off GDP.

One reason for the lost jobs is that companies need to divert funds to securing adequate water. A rise in water-borne diseases will also start to have an economic impact. Americans have been largely insulated from water-borne diseases, but this won’t last if we can’t keep our water supplies uncontaminated. It’s estimated that over the next five years water-borne diseases will cost the economy about $250 million, with disease and costs continuing to rise into the next decade.

Fracking encapsulates some of the trade-offs among food, energy, and water while shining a spotlight on the need to protect water supplies. The chemicals it uses to propel water into shale eliminates freshwater from the hydrological system. And fracking is concentrated in some of the driest parts of the country—including areas with the fastest population growth—where water for households and agriculture is in increasingly short supply.

The only solution is crash efforts to improve water infrastructure in parched parts of the U.S. and to create better infrastructure for distributing water throughout the country. Remarkably the price of water remains exceedingly cheap here at less than a half cent per gallon. But that is changing quickly. Since 2010, water prices to consumers have risen by 33 percent, outpacing almost all other goods and services. Expect that rate to accelerate sharply in the years to come.

This discussion is just a drop in the bucket in terms of diving into the multiple issues involving water. The bottom line, though, is that we need to do a lot more to protect our water supplies. We review six stocks in our The Complete Investor newsletter that are likely to be big beneficiaries including three of the most aggressive plays, which potentially could see explosive gains in coming years.