Supposedly a small tub or kiddie pool is enough. Supposedly Indian Runner ducks are quiet and lay lots of eggs. (We also got one Rouen, for variety.) Supposedly they coexist peacefully with chickens if given adequate space. Supposedly I am getting bids on a big wooden fence this week so that our neighbors and their dogs won't have to look at our barnyard. I stood there in the dimly lit poultry shed at Larsen's Feed and said, sure, why not.
In any case, we'll do our best, just like we have with the chickens. Poor little ducklings.