Home Postcodes by state WA 6058 Postcode 6058 6058 is the postcode for Forrestfield, WA. Localities with postcode 6058ForrestfieldWA Postcode 6058 State or territory Western Australia (WA) Localities 1 Council area Kalamunda Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6057 · Postcode 6059