Touted as the world’s fastest portable water purifier, the Grayl Geopress allegedly removes all pathogens from contaminated water, as well as pesticides, chemicals, and heavy metals, to ensure your drinking supply is in the backcountry. First, remove the cap-filter component and fill the bottle with water. Next, reinsert the cap-filter piece and push down, forcing water through the purifying cartridge into the inner, 24-ounce bottle. Then you drink. Like we said, easy. The cartridge is good for 350 uses.