Home Postcodes by state SA 5231 Postcode 5231 5231 is the postcode for 3 localities in SA: Chain Of Ponds, Kersbrook and Millbrook. Localities with postcode 5231Chain Of PondsSAKersbrookSAMillbrookSA Postcode 5231 State or territory South Australia (SA) Localities 3 Council area Adelaide Hills Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5223 · Postcode 5232