I don't use the galvanized ones because of the rusting & I occasionally put ACV in their waterers & that eats the metal out of them. I have 2-35 pound hanging feeders in my laying coop that are made of galvanized metal, those are fine.
We put water in our long sled and put it under the trampoline so it's in the shade.Works great for an outside waterer.
Inside we have a big metal waterer, kinda like the plastic one everyone's been possting pics of, but better.
metal one I have rusted first yr.