I usually don't drink bottled water at home any more since I've decided it's environmentally unfriendly (all that fuel moving it around) and financially unattractive. The tap water here isn't bad, so I drink it. If it were worse I'd get an RO system.

In the car, though, I've experimented with different kinds of containers and settled on 0.5 liter bottled water that I buy in 24-packs, usually for about $5 for 24. I don't rotate them but just drink them when I feel like it and replenish when the supply in the car starts getting low, which ensures that they are always reasonably fresh. Sometimes the 24-packs contain four wrapped 6-packs and I prefer that, since there's fewer loose bottles at any moment. But I generally don't buy individual 6-packs since that usually costs a lot more.

I looked at 7-gal Aqua-tainers at REI (mentioned in other thread) and it seemed to me that they were not well sealed, especially around the air vent, so I figured they'd leak in the car. I could see using them at home but the 1-gal bottles that I'm using are "free" while the Aqua-tainers are around $15 each. So I've stayed with the 1-gal bottles at home. In the car I've found the 0.5 liter bottles to be very handy and economical, and even if a few leak or spill, they won't ALL spill. So I plan to stick with them.

Those 6 packs are the best there are 3 of them in my car now. I drink the bottled water at college, the tap water is very questionable. <img src="/images/graemlins/confused.gif" alt="" />

I use the 6-packs (of 0.5l) for car-camping. I use 4-packs of 2-litre for contingency storage at home. The larger bottles are cheaper, without being more than I think I can drink in a day or two. I usually drink about 1L per day, so a 4L bottle would be pushing it. I like shop-bought water because it has a use-by date marked, and because it's convenient.