How do I identify a snail to be a land or water snail?

My brother found a snail and wants to keep it as a pet. I am assuming that it is a land snail, but if it is a water snail I do not want to kill it by depriving it of water. Thanks for your help=)|||i don't really know but i think you should put it in like a tank and give it a dish of water and if u find it always in the water dish than its a water snail if not its a land snail|||if you hate snails like i do you should tell him that the snails have sharp teeth %26gt;:)|||look it up on google.com