Buying surplus jerry cans brings up an issue. Fuel cans look just the same, and using exterior can racks does promote some confusion about military protocols. We only kept fuel in outside racks, and units would stencil them "mogas" vs "water" to cut down on mistakes. The luxury of camping in deserts allows exterior water carry, chipping an inch of frozen trail gunk off them to get water in the (in)temperate arboreal zone, not so much. They went inside - our "luggage", ie, duffel bags, went topside, rain or shine. It cut down on handling slick muddy cans.
I see a lot of surplus cans for sale, and effort is made to segregate them by use. Used cans with no markings deserve the sniff test. Polymers can get contaminated, cutting boards were one recent discovery harboring bacteria much longer than thought. It might behoove us to use separate and obvious containers in different colors - I've seen the mistake of filling a canteen with diesel when tired and in a rush.
Btw, Ive slung my share, if you are over 45 or have skeletal injuries, 5G cans are no fun, and if children are along, it leaves Mom and Dad dispensing and refilling. The spouts are great for potable water, an electric pump for grey water, too as its likely in a 20g or larger. Making that distinction seem to help, and that Brix has a competitor in Blox shows how the market is moving. Look for "prepper" suppliers having sales. If they are useful at home you extend the value of your dollar.