Over the last decade there has been tremendous progress in developing water purification equipment for troops out in the bush. In many remote locations the water supply often has to come by air (parachute or helicopter) and if you have to deliver water it’s very expensive. So cheap, lightweight devices that produce clean water from local stuff are much appreciated. More equipment like this has been showing up in the last decade.
The latest bit of water purification gear is the WaterGen Spring. This is a 12 kg (26 pound) battery powered unit that is designed to be back packed. Spring can produce 40-55 liters (over 10 gallons) of clean water an hour and 180 liters (45 gallons) on one battery charge. This new device has proved popular with police (especially in Israel, where Spring is made) and foreign aid organizations because it is a lightweight and cheap way to provide water in areas where there is little of it to begin with and what is there is dangerous to drink unless treated first.
This need is nothing new. 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 delivering clean water or purification equipment. This is expensive, and the troops who don't get clean water are forced to drink the local stuff and get sick.
There is a lot of enthusiasm for portable purifiers, as this finds a market among hikers and campers. Back in 2009, a British inventor created a portable (640 gr/1.4 pounds) water purification device (the "Lifesaver") that can hold nearly a liter (25 ounces) of purified water and can produce over two liters 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 liters of pure water, free of all known impurities.
The Lifesaver cost $229 back then and was issued to British troops in Iraq and Afghanistan. American troops 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.
Even locals find devices like Spring and Lifesaver attractive, even with the high cost. That’s because throughout history the biggest killer of all has been tainted water.