Not that I own ten, Just askin for a friend.

Well, it depends.

If it is EDC to and from your work, it is overkill. But if you are traveling 100 miles on seldom travel roads in July/August, they are not enough.

Or maybe you would be better off with 3-4 larger ones, or a camelbak.

Ten water bottles, of what capacity? There is a big difference between those wimpy 27 oz bottles and a decent sized liter container.

In desert conditions, in the summer, ten could be insufficient. Most of the time, ten decent sized bottles would be more than enough, given reasonable water sources (such as you would find in the Land of Canoe Dogs and Byrd Hunter).

I mean owning ten

I don't even buy them intentionally and I have 6, some are bought some received free at events, even an old evil BPA bottle.

Ten is just a good start (says the old desert rat)).

DW says I should try to cut my water bottle collection DOWN to ten. It's going to be mighty tough to do. I needs 'em all!

Hahaha! I can probably reach 10 bottles from where I'm sitting at the PC right now!

I like them, and almost have a problem with them. I like keeping them filled and in the fridge, it makes me feel secure, lol. I also refill any plastic bottles I use with the #1 plastic. Those go in my emergency supply. Also, if I take a plastic bottle in my truck and forget it there, if it's mostly full, I leave it in there instead of taking it in (so it's sort of an Extra extra water supply). I get a little paranoid about water. I feel like my supply is way too low this far into hurricane season.