While open defecation has well known health risks, toilets with sewage pits come with their own drawbacks. One of them is the contamination of ground water due to sewage leachate -- the water that seeps into the soil from the pit and has extremely toxic levels of nitrates, ammonium and organic carbon. These toxins are known to contaminate ground water making it unfit for drinking. Now scientists have designed a twin-pit toilet system that reduces the levels of nitrates, ammonium and organic carbon in the sewage water before it is being absorbed by the ground. This treated water, the researchers say, have low levels of toxins, making it safe and saving water bodies from contamination due to sewage.