I copied this from here.http://www.bestwdw.com/parks/restrooms
I do not know how accurate it is.
Best Family Restrooms
Magic Kingdom
First aid station near Casey's Corner, The lower level of Cinderella’s Royal Table, Pirates of the Caribbean exit area, Splash Mountain exit area, behind Pinocchio Village Haus, to righthand side of Space Mountain.
Epcot
First aid station near Odyssey, opposite Test Track, Canada Pavilion, Morocco Pavilion, Germany Pavilion, Norway Pavilion.
Avoid the restroom inside The Land, it's often a very crowded area.
Disney's Hollywood Studios
First aid station at the park entrance, Star Tours, near Soundstage 3, Rock 'N' Roller Coaster, near Fantasmic theater.
Avoid the restroom near The Twilight ZoneTower of Terror, often a very crowded area.
Disney's Animal Kingdom Theme Park
Discovery Island, near Flame Tree Barbecue, Harambe Village, in the Mombasa Marketplace, Conservation Station, Asia Restrooms near Maharajah Jungle Trek, Chester and Hester's Dinosaur Treasures in Dinoland U.S.A.
Blizzard Beach - To the rear of the locker room.
Typhoon Lagoon - Near Guest Services