Since its for a remote property that you will only visit on occasion, I'd use the soap drums (thoroughly rinsed) for toilet water, clothes washing, hot tub, and possibly garden irrigation. I'm certain most water use is not for drinking for most folks.
For drinking, I really believe you'd only need one or two drums, so the pepsi syrup drums or any other food product drum would be a safe bet.
Many survivalists here in Utah, and new $40 blue HDPE drums for basement drinking water back-up storage is popular. Havent done this myself, so I don't know if its a good idea.
