One in 6 people in the world faces a clean-water shortage, according to the United Nations—so scientists are proposing a quick fix. Dirty water can be rendered drinkable using a few odd ingredients: Sun, salt, dirt, and lime, NPR reports. The sun's rays can kill the germs in bottled water left out for six hours—but for this to work, the water has to be transparent. "You need to be able to read a newspaper through it. That means it's clear enough for the UV radiation to penetrate and kill the pathogens," says an expert.
The solution: Add salt and a type of clay soil known as bentonite. The added soil is electromagnetically attracted to the salt. That soil mixes with the existing dirt and the salt brings everything to the bottom of the bottle, where it settles. Worried about the taste? Add some lime, which offers the added benefit of speeding the removal of bacteria like E. coli. You'll still have to leave the water in the sun, but a study found lime could cut disinfection time to a half hour.