In the same light, commercial dryer drums can be lined and used as large tanks. You need access to a commercial junk yard, but there is all sorts of good stuff if they let you in to scavenge.

My town has a recycle center that people drop off all sorts of things. You can take what is there as well as drop off. There are always refer's and freezers. A big freezer would work just as well, and these hold water. Ihad a freezer disaster, so I know that for a fact.