My question is in regard to use. The only documented ones that I have seen were used for petroleum products for signal corps, home oil lamps, etc. I have never seen a documented copper canteen for water, and, considering the scarcity of that resource in the south, would question why it woyld be used. One canteen of copper could make quite a few percussion caps.
There may well be a documented copper water canteen somewhere, but I have personally never seen one, and as I said, the WHY factor would tend, to me, to negate it's consideration of use as anything beyond a curio example.