I carry the MSR Sweet-water filter, it comes with Chlorine ViralStop. It was about $120 Canadian, and I've had it for well over a year now, most of the parts are pretty pricey ($60 for a replacement filter cartridge, and $20 for silt stopper). But it's light, compact, easy to use and I've been told by some experts that with the ViralStop, it's able to purify any fresh water in North America, Australia and Europe. I'm not sure about Africa, Asia or South America though, I'll have to do some research.
But I also carry the Katadyn Micro-pur tablets. Apparently Micro-pur is approved by the American FDA as the ONLY water purification product that can make your water truly safe to drink. Over here in Canada those cost about $20 for 30 tablets (each tablet will purify 1 litre of water).
For the question... I'd boil my water in India, even with my filter and tablets, just to be safe. I like safety when it comes to my own health.. when it comes to others... let em go ahead and not boil it