Access to drinking water is a major issue in the developing world, especially in Africa, where dirty water kills more people than violence. Solar water purification is a tried and true method of using UV rays to kill harmful bacteria and viruses in water, and we've featured a good number of designs that harness the process (see a few at the left). The Solar Bag, created by Ryan Lynch and Marcus Triest is another in the genre that stands out.
The idea is pretty simple: fill the bag with 2.5 gallons of water, sling it over your shoulder, and let the sun do its work while you walk. Lynch and Triest say the idea takes into account how far some people need to walk to access even dirty water. Within six hours, the water in the bag is safe to drink.
The Solar Bag is made from high clarity polyethylene, designed to maximize the passage of UV rays, on one side. The other side is black polyethylene, which reflects those rays back through the water and heats the water, speeding up the purification process. There's also a nylon shoulder strap and a spigot at the bottom to release clean water. For immediate purification, Lynch and Triest have added an attachable balloon pump with a filter.
What's really impressive, according to Lynch, is that the materials they use will cost as little as $5 per bag, or even less, depending on the scale and efficiency of production. The bags could be made where they would be used, cutting down on shipping costs and emissions, making the Solar Bag a win-win.