Home Postcodes by state WA 6603 Postcode 6603 6603 is the postcode for 5 localities in WA: Konnongorring, Lake Hinds, Lake Ninan, Mocardy and Wongan Hills. Localities with postcode 6603KonnongorringWALake HindsWALake NinanWAMocardyWAWongan HillsWA Postcode 6603 State or territory Western Australia (WA) Localities 5 Council area Goomalling; Wongan-Ballidu Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6575 · Postcode 6605