August 20,2008:  Since there have been armies, the largest single cause of casualties has been bad water. Not the enemy, but water borne diseases. Modern armies devote a lot of transport to moving clean water, and purification equipment. This is expensive, and the troops don't always get clean water, drink the local stuff, and get sick.

A British inventor has created a portable (1.4 pounds) water purification device (the "Lifesaver") that can holds 25 ounces of purified water, and can produce over two quarts a minute. The Lifesaver looks like a thermos bottle, and is manually operated like a pump. A set of filters can produce over 4,000 quarts of pure water, free of all known impurities.

The Lifesaver costs $229, and was issued to British troops in Iraq and Afghanistan. American troops have bought Lifesavers with their own money. That's because they find the Lifesaver more effective than water purification pills (which produce water that tastes awful), or earlier portable purification devices.