We have a couple of 'turtle' plastic sandpits for the ducks (from freecycle/small ads)...
They get filled up/emptied out every other day.... the water either goes in my compost, or on the veg patch....
We got the turtles cos it meant I could lift up and empty out on my own without needing my hubby to help.
Eventually, we're looking to hook up some sort of hose and valve system through the bottom of them, then I don't have to bail out or tip into buckets to empty...