That looks different, but probably just rusty memory, from a previous post elsewhere.
I’d forgotten I posted it in that other spot. But it’s the same (though I may have added the 2″ overflow tube since then – that would be the only difference).
I thought about one or two larger containers, but decided to keep it closer to the house, and be able to make it more “modular” so I can add more if I want to, make modifications, etc. Hope you find what you’re looking for in your case. You certainly don’t get as much rain as we get, and you’ve got other weather factors to contend with as well (like winter).
Remember though, if you build yourself a black Berkey water filter system at least for drinking water, you should have no worries about the container not being food grade. And even if you’ve got a food grade container, if you’re collecting from a roof you’ve got to contend with the contaminants it adds to the rain water. So depending on what’s been in the container before, food grade plastic may not be quite as essential – particularly in a survival situation.