diff --git a/app/controllers/api/v3/facilities_controller.rb b/app/controllers/api/v3/facilities_controller.rb
index feb13fdb5c..a398036e0f 100644
--- a/app/controllers/api/v3/facilities_controller.rb
+++ b/app/controllers/api/v3/facilities_controller.rb
@@ -44,17 +44,29 @@ def force_resync?
   end
 
   def records_to_sync
-    Facility
-      .updated_on_server_since(other_facilities_processed_since, limit)
-      .includes(:facility_group)
-      .where.not(facility_group: nil)
+    if Flipper.enabled?(:regions_prep)
+      other_facility_records
+        .with_block_region_id
+        .includes(:facility_group)
+        .where.not(facility_group: nil)
+    else
+      other_facility_records
+        .includes(:facility_group)
+        .where.not(facility_group: nil)
+    end
   end
 
   private
 
+  # Memoize this call so that we don't end up making thousands of calls to check user for each facility
+  def block_level_sync?
+    return @block_level_sync_enabled if defined? @block_level_sync_enabled
+    @block_level_sync_enabled = current_user&.block_level_sync?
+  end
+
   def sync_region_id(facility)
-    if current_user&.block_level_sync?
-      facility.region.block_region.id
+    if block_level_sync?
+      facility.block_region_id
     else
       facility.facility_group_id
     end
diff --git a/app/models/facility.rb b/app/models/facility.rb
index 57fe234f0e..002c057ff2 100644
--- a/app/models/facility.rb
+++ b/app/models/facility.rb
@@ -49,6 +49,11 @@ class Facility < ApplicationRecord
     foreign_key: "assigned_facility_id"
 
   pg_search_scope :search_by_name, against: {name: "A", slug: "B"}, using: {tsearch: {prefix: true, any_word: true}}
+  scope :with_block_region_id, -> {
+    joins("INNER JOIN regions facility_regions ON facility_regions.source_id = facilities.id")
+      .joins("INNER JOIN regions block_region ON block_region.path @> facility_regions.path AND block_region.region_type = 'block'")
+      .select("block_region.id AS block_region_id, facilities.*")
+  }
 
   enum facility_size: {
     community: "community",