(From top) unsafe water and the water filter developed by the NCL.

When Bhupinder Walia wanted to provide clean drinking water to his staff at a remote village in Himachal Pradesh, he turned to the National Chemical Laboratory (NCL). The village had neither power nor clean water. The Pune-based NCL recommended a filtration system developed in-house, which eliminated bacteria and viruses from raw water and did not use electricity.

Called Purioin, the system differs from other conventional water filters because it needs no electrical power for filtration, and, so, is well suited for India’s 600,000 villages, most of which have neither water nor electricity. “Nearly 10-12 people have been drinking water from Purioin daily for a year now,” says Walia, who runs a food processing unit for a non governmental organisation (NGO) at Nagwein, a small village 20 kilometres north of Kulu. “The best thing about Purioin is that it needs no power. A hand pump will do,” says Walia.

Purioin’s brain is a membrane ? a thin film whose small pores serve as physical barriers preventing the passage of impurities. Water is cleaned of viruses and bacteria while passing through the membrane, which was developed by NCL’s polymer division. The membrane is so fine that only the tiniest of molecules (water and salt) pass through it. Larger molecules, viruses and bacteria remain on the surface of the membrane.

The membrane filter does not require electricity, unlike power-hungry membranes used in other filtration technologies such as reverse osmosis. NCL’s membrane filter, which received a US patent last year, works on gravity. “Water must flow from a minimum height of 30 feet or an overhead tank,” says Walia. Alternatively, a hand pump circulates water from a ground-level tank into separate modules, at a given pressure, in a tangential direction so that any large molecules or particles are pushed ahead and do not block the pores of the membrane. Pure water subsequently flows out. Moreover, NCL’s filter is much cheaper than those of other membrane technologies, says Subhash Devi, founder of the Pune-based Membrane Filters, which commercialised NCL’s technology and built a water filtration system around NCL’s membrane filter. Devi says that Purioin’s cheapest system, which pumps out a litre of water every minute, costs Rs 5,500 ? around a third of what a membrane-based residential water filtration system of competitors such as the Mumbai-based Eureka Forbes and Ion Exchange costs.

Used in a wide variety of applications in the pharmaceutical and chemical industries, membrane technology was developed in the West decades ago. Membranes were used in industrial processes, pharmaceutical plants and desalination projects that required a lot of power. India imported membranes from America and Japan, but they were very expensive and power-hungry. So R.A. Mashelkar, polymer scientist and head of the Council for Scientific and Industrial Research, decided to develop a membrane filter. The membrane is composed of a chemical solution and is pasted on a back up material, in a process called polymerisation. The trick lies in the thin film withstanding continuous water pressure and maintaining uniform porosity throughout the membrane. “Other membrane-based filtration systems use electricity. We don’t,” says NCL’s Dr P.K. Ingle. “Our filter also cleans all viruses. We have validation from leading research institutes.” Water supplied by public utilities in India may not be completely safe because by the time it reaches a consumer it passes through old pipelines, unhygienic storage systems, bad plumbing lines and so on. Water is quite unsafe for drinking because of the possibility of suspended solids, worms, spores, cysts of amoebas, pathogenic germs, colloidal impurities, unwanted bacteria and at times viruses of water prone diseases. Ingle says that the membranes and modules developed at NCL were validated by the Agharkar Research Institute and the National Institute of Virology (NIV) in Pune and by the National Environmental Engineering Research Institute (NEERI). “Other filtration systems remove larger bacteria but allow the smaller ones to pass through. Our technology removes the smallest viruses and bacteria,” says Devi.

Membrane Filters sold 200 Purioins last year, largely to NGOs, which use it in villages and in disaster zones such as the tsunami-devastated areas. But funds are the biggest worry. “The government must provide the initial boost, as this filter system provides the solution to India’s drinking water problems,” says Devi.