Where can I get water tested in Kolkata - Which purifier is the best - RO+UV or RO only or RO+UF ?

Dear Sir,

I am residing in Bansdroni area in Kolkata. I wish to know a lab in Kolkata, where I can get the water tasted. I want to know which purifier is better RO+UV or RO only or RO+UF.

Please guide immediately.