I just refill water bottles with water from the tap.

Oooh!! I do envy you (or, possibly, I'm jealous of you) The tap water round here is so vile that even I can't bring myself to do that - it tastes as though it has dripped from Lucifer's boots. The best I can manage is to buy the 5 litre bottles of water and refill my small bottle from that. I saves quite a lot of cash, that way, even allowing for my shaking hand causing spillage.