Water, water everywhere ... That troops can't drink.

• Author: Parsons, Dan
• Position: Inside Science + Technology

Napoleon Bonaparte is credited with saying that an army marches on its stomach. But an even more important tactical necessity than food is the availability of clean drinking water.

The military's plan to hydrate troops in Afghanistan has largely been to supply them with bottled water, rather than purify available sources. It has been a costly endeavor.

A number of large, pre-staged water purification systems have also been deployed. But those systems are transportable only by vehicle and are not suited for the sort expeditionary missions the Marine Corps is expecting to perform post-Afghanistan.

Industry and several Defense Department-run laboratories,3 are studying technologies that will reduce troops' reliance on water resupply in the field, which counts for more than half of the military's logistical burden in Afghanistan.

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Purification technologies that can be carried by individual soldiers or Marines have become a sort of Holy Grail in the race to lighten troops' load and the logistical burden of expeditionary operations.

"The challenge is to arrive at a small system that's portable, packable wherever you decide to take it, that can remove harmful micro-organisms and dissolved salts," said Andrew Sabota, a branch project officer for the Marine Corps Warfighting Laboratory. "But when you reduce the size and power of these systems, the tradeoff is you're reducing the ability to get rid of those salts."

Big, powerful systems are great at doing just that, and can desalinate seawater to boot.

The Lightweight Water Purification System currently in use by the Marine Corps in theater fits in a Humvee and can produce up to 125 gallons of potable water per hour, but weighs a couple thousand pounds. The Tactical Water Purification System can clean 1,200 to 1,500 gallons of water an hour but must be hauled by a 7-ton truck and requires an engineer support unit to set up.

Those are too big and too heavy for units on the move.

The Warfighting Lab is studying the use of what it calls the Small Unit Water Purification System--essentially a U1-fledged water treatment facility inside an 80-pound suitcase.

Capable of pumping out 750 gallons of potable water every 24 hours, the SUWP can support the fluid-intake needs of about 250 Marines, even in arid environments, Sabota said.

It uses four types of filters--reverse osmosis, ultraviolet light, carbon and sediment--to remove all contaminants from groundwater that ranges from fresh to...