Here's a low-cost water purifier for villages

Bengaluru, May 4 , 2015: A discarded sari, a few glass pipes and freely available sunlight are the only requirements for an innovative system that can provide safe drinking water to a rural household. The unique low-cost solar water purifier (SWP) does not require electricity and can be produced by village craftsmen, claim its developers at the Nimbkar Agricultural Research Institute (NARI), an NGO working at Phaltan in rural Maharashtra. Also, unlike commercially available water purifiers, the SWP does not suffer from problems like filter clogging or wastage of water, NARI director Anil Rajvanshi told IANS. Boiling the water is a recommended method to kill any disease-causing bacteria that may be present. But to boil the water, one requires electricity or other fuel. NARI's purification strategy exploits the fact that one need not have to really boil the water to make it germ-free. Low temperatures are sufficient for sterilising the water provided the temperatures are maintained sufficiently longer. "Our earlier studies have shown that water heated to only 50 degrees Celsius and maintained at that temperature for one hour, or heated to 45 degrees and maintained for three hours, becomes completely free of coliform bacteria," Rajvanshi said. The presence of coliform is an indication that pathogens (disease causing germs) are present. The bacterial colony count was done in the institute's microbiology lab according to international protocols, he said.