Home Postcodes by state WA 6718 Postcode 6718 6718 is the postcode for 2 localities in WA: Roebourne and Whim Creek. Localities with postcode 6718RoebourneWAWhim CreekWA Postcode 6718 State or territory Western Australia (WA) Localities 2 Council area Karratha Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6716 · Postcode 6720