Home Postcodes by state SA 5725 Postcode 5725 5725 is the postcode for 2 localities in SA: Olympic Dam and Roxby Downs. Localities with postcode 5725Olympic DamSARoxby DownsSA Postcode 5725 State or territory South Australia (SA) Localities 2 Council area Roxby Downs Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5724 · Postcode 5730