0xp I really like this item.

It's not too big, but could still be used to bash someone with. It's not made of anything too exotic or do anything to powerful, but it always of use to any character. It has plenty of possibilities that a creative DM could talior to his game.

One thing that I'd like to be cleared up though. The stone does not need to be immersed in a liquid to absorb it, just be in contact with it, so does it draw the liquid in like a vacume cleaner?

Some things DM's might consider doing could be alter how much the canteen stone can hold by a factor of what it's made out of. Ordinary rock would be the one gallon, but slate might hold two or three, marble could hold five to ten, a fist-sized chunk of quartz would carry quite a bit, precious stones would be ridiculously huge and hold a ridculious amount.

If the stones don't need to be squeezed by hand they could be used to create a running water system. Also, some interesting and creative effects could take place if they are broken, making them possible siege weapons as well.

This is an good example of how items should be. They can be more powerful or less, but those of you posting items of late should take note of this submission and use it as a benchmark.