Home Postcode finder SA Back Valley Back Valley postcode SA Back Valley is a locality in South Australia covered by postcode 5211. Postcode 5211 State or territory South Australia (SA) Region Sa Subs Near 2 Add a free Back Valley business listing Be the first listing in Back Valley Common questionsWhat is the postcode for Back Valley?Back Valley, SA has the postcode 5211.What state is Back Valley in?Back Valley is in South Australia (SA).Does postcode 5211 cover more than one suburb?Yes. Postcode 5211 covers 12 localities, so the postcode alone does not identify Back Valley. Browse other postcodes in South Australia, or widen the search to every Australian postcode.