Water, calcium, vitamins, and bears

Well, no bears, but I was curious about personal preferences. Tonight I was browsing through the old Leopard Gecko posts and was curious as to what you felt was the best. I suppose I could do a poll, but I'm not sure of all the variables to include. I'm sure this is an OT, but as my question is soley for Leo's, I thought I'd toss in this ring.

What do you use as water? Tap, distilled, bottled, spring, fizzy, gatorade? I read about all the preservatives in tap water for humans that can kill the average black mamba and how we shouldn't use it for our reptiles, but I was wondering if people actually buy the over the counter stuff that promises to eliminate all the anti-reptile chemicles.

RepCal seems to be a common calcium supplement, but do other's have better luck or recommend a different type? What about vitamins?

What type of substrate should I ***oops*** sorry. I know that question.

Thanks in advance!
Julie