Home Postcodes by state WA 6124 Postcode 6124 6124 is the postcode for Jarrahdale, WA. Localities with postcode 6124JarrahdaleWA Postcode 6124 State or territory Western Australia (WA) Localities 1 Council area Serpentine-Jarrahdale Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6123 · Postcode 6125