I bought a bunch of 7 gal & 5 gal containers from emergencyessentials.com. They're pretty sturdy and shipping is very reasonable. Down the road I'd like to add a couple of 55 gal containers but I've held off due that same issue- a 55 gal drum full of water weight around 440 lbs! The 5 gals are easier to move and simpler to rotate.
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“I'd rather have questions that cannot be answered than answers that can't be questioned.” —Richard Feynman