How much water would waterfowl (pair of ducks, pair of geese. Maybe another bird if possible) actually need? I want to spend my non-bird time designing stuff for them, and my family has done plumbing and even pond maintenance before (a pair of ducks moved in after the big sump-pump and the tiny pond wasn't ruined at all. They left--or died--thanks to the raccoons). What's the minimum of water needed for those birds? The biggest problem was plants disappearing overnight. I'd like to know about how to protect those too, if possible. I need those to keep the soil and rocks in place and help filter the nitrogen out a bit.