Technically all water is already drinkable, it's just that the contaminated stuff might try to tear your @$$hole off on the way out. Enter Proctor and Gamble's Purifier of Water, magic packets that make any water drinkable enough to not give you the runs. The fast-walks, MAYBE. The company's non-profit division hopes to be passing out 200-million packets of the stuff yearly by 2020.
Greg Allgood tears open a small sachet and dumps the powder into a large plastic container filled with brown, murky water. After about five minutes of stirring, clumps of sludge form and sink to the bottom as the water starts to clear.
Iron sulphate is the coagulant that pulls together soil, heavy metals and parasites. Chlorine - a precise 80 granules per sachet - kills viruses and bacteria, including those that cause cholera.
One sachet purifies 10 liters (2.6 gallons) of water, enough for five people for one day, and it does not matter that the container and straining cloth are not clean. Shipping, duties and distribution, education and training by the groups on the ground take the final cost to about 10 U.S. cents per packet.
Oh man, I drank brown water one time -- it was actually pretty good. "That was chocolate milk." It was brown water! "It came in a Nesquik bottle." I DUG IT OUT OF A MUDDY HOLE IN MY BACKYARD. "Stop lying." I BLEW BUBBLES IN IT.
Thanks to Dizzle, who bet me I wouldn't drink road runoff water but I did and now I'm stronger because of it (plus blind in one eye).