Home Postcodes by state SA 5242 Postcode 5242 5242 is the postcode for Balhannah, SA. Localities with postcode 5242BalhannahSA Postcode 5242 State or territory South Australia (SA) Localities 1 Council area Adelaide Hills Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5241 · Postcode 5243