Home Postcode finder SA Merriton Merriton postcode SA Merriton is a locality in South Australia covered by postcode 5523. Postcode 5523 State or territory South Australia (SA) Region SA Outer Suburbs Add a free Merriton business listing Be the first listing in Merriton Common questionsWhat is the postcode for Merriton?Merriton, SA has the postcode 5523.What state is Merriton in?Merriton is in South Australia (SA).Does postcode 5523 cover more than one suburb?Yes. Postcode 5523 covers 10 localities, so the postcode alone does not identify Merriton. Browse other postcodes in South Australia, or widen the search to every Australian postcode.