it depends
I have a friend whose ducks have lived 14 years! Ducks average seven (plus or minus) years. 2nd answerer says: Ducks that are well-cared for can live 20+ years!
7+ years, if you take care of the duck really good. Some healthy ducks can live into their 20's.
only two years
i have heard that ducks live for 2 and over to about 7 years