Home Postcode finder WA Lake Ninan Lake Ninan postcode WA Lake Ninan is a locality in Western Australia covered by postcode 6603. Postcode 6603 State or territory Western Australia (WA) Region Wa Subs 4 Coast Add a free Lake Ninan business listing Be the first listing in Lake Ninan Common questionsWhat is the postcode for Lake Ninan?Lake Ninan, WA has the postcode 6603.What state is Lake Ninan in?Lake Ninan is in Western Australia (WA).Does postcode 6603 cover more than one suburb?Yes. Postcode 6603 covers 5 localities, so the postcode alone does not identify Lake Ninan. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.