Depends on the birds my calls do need water to swim in winter so i opt for small 3 GAL pans that i dump each night and refill several times daily. Frankly, my other larger mallard derived ducks would swim if i could do that for them too but my scovies will ice up so i opt to not keep swimming water out, they are neither mallard derived nor heavily waterproofed.
I still think those rubber livestock pans are the best, you can hammer the crud out of them and they easily hold water since they come in many sizes.
I agree. I use the 3 gallon pan for letting the ducks splash about in and a 2 gallon one for drinking/splashing. They do work really well. You just pick them up when frozen, drop on ground, and there goes the ice! It's great. At night, they have a heated dog dish with a partial cover to keep them from getting into it. (They are inside a greenhouse at night.)
My muscovies do like the 3 gallon pan for splashing. It's probably not essential for them to have, but on warmer days I let them splash. A couple of days ago, I went out a bit late and one was sitting in the 2 gallon pan. I was afraid she had sat too long and frozen down. Luckily, she was just sitting in slush. I make sure to go out sooner now!