Home Postcodes by state WA 6625 Postcode 6625 6625 is the postcode for Merkanooka, WA. Localities with postcode 6625MerkanookaWA Postcode 6625 State or territory Western Australia (WA) Localities 1 Council area Morawa Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6623 · Postcode 6627