>>163196164 ounce steel klean-kanteen. It's a half gallon, so you only fill it twice per day. It doubles as a pot. It is durable as fuck. I've had the same one for like 6 years and it only has a few small dents in the bottom. It's one of the best pieces of equipment you can have next to other basics like a tarp and cordage and fire making material.
PS - The best fucking part - I got it in the mail for free because it was shipped with beer in it to the apartment that I was living in, under no name and no return address. I think it had something to do with the previous tenant. The package was leaking beer all over and I had no return address so I was like oh fuck it I can't just toss this, so I opened it. Low and behold, a beautiful half gallon steel container full of fucking dark beer. I drank the beer and I've used the fuck out of the container almost everyday for years. Shit was bizarre but perfect.