Mr. Nigam Hindi is not a National Language. It is one of the Official Languages of Union of India. I am not justifying that people should learn Tamil when you are in Tamilnadu, but i do see a lot of hype here about you are not given Water when you don't ask in tamil and that is unbeleivable. Do not take one or two examples and show hatred toward the entire community.
Learning a language should be reciprocative. If you dont want to learn any Dravidian Languages then do not push the concept of South Indians learning Hindi. Just as a FYI, I am a tamilian who can read, write and speak Hindi.