My chickens and ducks live together without any issues. Just be prepared to be CONSTANTLY cleaning out ANY source of water.
I've tried and tried to find a solution to this, because the ducks just have to make any water source muddy and it ticks the chickens off, because they prefer their water clean. I've tried giving the ducks a wading pool, and the chickens a 5 gallon waterer, nope, both containers were muddy the nest day. So wherever you keep ducks, just know you'll be cleaning out the water dishes daily.
Just be careful and watch the ratio of birds. I once tried to introduce 3 teenage rouen ducks to a coop of 6 chickens, and the chickens attacked the ducklings mercilessly. So be aware that chickens can be very aggressive in the pecking order.
-Kim