diff --git a/src/main/java/org/qortal/arbitrary/misc/Service.java b/src/main/java/org/qortal/arbitrary/misc/Service.java
index e0caa2a5..b53ab7ca 100644
--- a/src/main/java/org/qortal/arbitrary/misc/Service.java
+++ b/src/main/java/org/qortal/arbitrary/misc/Service.java
@@ -249,6 +249,10 @@ public enum Service {
         return this.requiresValidation || this.single;
     }
 
+    public boolean isPrivate() {
+        return this.isPrivate;
+    }
+
     public static Service valueOf(int value) {
         return map.get(value);
     }
@@ -258,6 +262,37 @@ public enum Service {
         return new JSONObject(dataString);
     }
 
+    public static List<Service> publicServices() {
+        List<Service> privateServices = new ArrayList<>();
+        for (Service service : Service.values()) {
+            if (!service.isPrivate) {
+                privateServices.add(service);
+            }
+        }
+        return privateServices;
+    }
+
+    /**
+     * Fetch a list of Service objects that require encrypted data.
+     *
+     * These can ultimately be used to help inform the cleanup manager
+     * on the best order to delete files when the node runs out of space.
+     * Public data should be given priority over private data (unless
+     * this node is part of a data market contract for that data - this
+     * isn't developed yet).
+     *
+     * @return a list of Service objects that require encrypted data.
+     */
+    public static List<Service> privateServices() {
+        List<Service> privateServices = new ArrayList<>();
+        for (Service service : Service.values()) {
+            if (service.isPrivate) {
+                privateServices.add(service);
+            }
+        }
+        return privateServices;
+    }
+
     public enum ValidationResult {
         OK(1),
         MISSING_KEYS(2),
diff --git a/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataCleanupManager.java b/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataCleanupManager.java
index 9d57ce8a..e0c62acb 100644
--- a/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataCleanupManager.java
+++ b/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataCleanupManager.java
@@ -346,6 +346,10 @@ public class ArbitraryDataCleanupManager extends Thread {
 	/**
 	 * Iteratively walk through given directory and delete a single random file
 	 *
+	 * TODO: public data should be prioritized over private data
+	 * (unless this node is part of a data market contract for that data).
+	 * See: Service.privateServices() for a list of services containing private data.
+	 *
 	 * @param directory - the base directory
 	 * @return boolean - whether a file was deleted
 	 */
diff --git a/src/test/java/org/qortal/test/arbitrary/ArbitraryServiceTests.java b/src/test/java/org/qortal/test/arbitrary/ArbitraryServiceTests.java
index 45960a25..33632b4a 100644
--- a/src/test/java/org/qortal/test/arbitrary/ArbitraryServiceTests.java
+++ b/src/test/java/org/qortal/test/arbitrary/ArbitraryServiceTests.java
@@ -29,6 +29,7 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.nio.file.StandardOpenOption;
+import java.util.List;
 import java.util.Random;
 
 import static org.junit.Assert.*;
@@ -503,4 +504,20 @@ public class ArbitraryServiceTests extends Common {
         assertEquals(ValidationResult.OK, service.validate(filePath));
     }
 
+    @Test
+    public void testGetPrivateServices() {
+        List<Service> privateServices = Service.privateServices();
+        for (Service service : privateServices) {
+            assertTrue(service.isPrivate());
+        }
+    }
+
+    @Test
+    public void testGetPublicServices() {
+        List<Service> publicServices = Service.publicServices();
+        for (Service service : publicServices) {
+            assertFalse(service.isPrivate());
+        }
+    }
+
 }
\ No newline at end of file