Query regarding water purifier

Which is the best residential water purifier?

Hello, I am living in a gated community where we have around 300 families. We use groundwater during winter and we buy water from outside during the absence of groundwater. So I am not sure how it would help me to test my water for buying a purifier. So far, I have been buying water bottles but would like to buy a purifier. Please give me some direction and what options I have and can consider.

Thanks Gopi