Ratan Tata was once inspired to build a cheap car when he saw a family of four balanced on a bicycle in his native India. Now that the Tata Nano "people's car" is a reality, the business tycoon has unveiled an even more useful product for India and the world. Globally, over a billion people do not have daily access to safe drinking water. The types of water delivery systems we use are prohibitively expensive for many countries. Around 380,000 children in India alone will die this year from diarrhea, mainly caused by the water they consume. An estimated 85% of people in India do not filter their water before drinking. If there were some way to make filtering easy and affordable for them, it would prevent many cases of illness due to waterborne pathogens.

100tataTata Chemicals, a division of Ratan Tata's business empire, has unveiled their latest gadget, a water filter called the Tata Swach. The technology isn't all that complicated. The Tata Swach uses rice husk ash (a product very abundant in India) coated with silver nanoparticles to filter microbes from the water. Rice husk ash has been used for centuries to clean teeth. Now it can clean water to be used for cleaning teeth. The advantages of the Tata Swach include the fact that it needs no electricity. India has 400 million people who are not connected to the electrical grid, and those tend to be the same people who aren't served by a water system. The Tata Swach unit hold 9.5 liters at a time and will clean 3,000 liters of water on one filter cartridge, enough to last a family of five about a month.

The Tata Swach will sell for about £10 each, or a thousand rupees. Replacement filters will be about 30 rupees.

See also: LifeStraw