diff --git a/lib/charms/data_platform_libs/v0/s3.py b/lib/charms/data_platform_libs/v0/s3.py
index 7beb113b6d..f5614aaf6b 100644
--- a/lib/charms/data_platform_libs/v0/s3.py
+++ b/lib/charms/data_platform_libs/v0/s3.py
@@ -137,7 +137,7 @@ def _on_credential_gone(self, event: CredentialsGoneEvent):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 4
+LIBPATCH = 5
 
 logger = logging.getLogger(__name__)
 
@@ -212,7 +212,7 @@ class S3CredentialEvents(CharmEvents):
 class S3Provider(Object):
     """A provider handler for communicating S3 credentials to consumers."""
 
-    on = S3CredentialEvents()  # pyright: ignore [reportGeneralTypeIssues]
+    on = S3CredentialEvents()  # pyright: ignore [reportAssignmentType]
 
     def __init__(
         self,
@@ -481,6 +481,18 @@ def set_s3_api_version(self, relation_id: int, s3_api_version: str) -> None:
         """
         self.update_connection_info(relation_id, {"s3-api-version": s3_api_version})
 
+    def set_delete_older_than_days(self, relation_id: int, days: int) -> None:
+        """Sets the retention days for full backups in application databag.
+
+        This function writes in the application data bag, therefore,
+        only the leader unit can call it.
+
+        Args:
+            relation_id: the identifier for a particular relation.
+            days: the value.
+        """
+        self.update_connection_info(relation_id, {"delete-older-than-days": str(days)})
+
     def set_attributes(self, relation_id: int, attributes: List[str]) -> None:
         """Sets the connection attributes in application databag.
 
@@ -580,6 +592,17 @@ def s3_api_version(self) -> Optional[str]:
 
         return self.relation.data[self.relation.app].get("s3-api-version")
 
+    @property
+    def delete_older_than_days(self) -> Optional[int]:
+        """Returns the retention days for full backups."""
+        if not self.relation.app:
+            return None
+
+        days = self.relation.data[self.relation.app].get("delete-older-than-days")
+        if days is None:
+            return None
+        return int(days)
+
     @property
     def attributes(self) -> Optional[List[str]]:
         """Returns the attributes."""
@@ -613,7 +636,7 @@ class S3CredentialRequiresEvents(ObjectEvents):
 class S3Requirer(Object):
     """Requires-side of the s3 relation."""
 
-    on = S3CredentialRequiresEvents()  # pyright: ignore[reportGeneralTypeIssues]
+    on = S3CredentialRequiresEvents()  # pyright: ignore[reportAssignmentType]
 
     def __init__(
         self, charm: ops.charm.CharmBase, relation_name: str, bucket_name: Optional[str] = None
diff --git a/src/backups.py b/src/backups.py
index 49ac87b84d..b1785b3a1b 100644
--- a/src/backups.py
+++ b/src/backups.py
@@ -832,6 +832,7 @@ def _render_pgbackrest_conf_file(self) -> bool:
             stanza=self.stanza_name,
             storage_path=self.charm._storage_path,
             user=BACKUP_USER,
+            retention_full=s3_parameters["delete-older-than-days"],
         )
         # Render pgBackRest config file.
         self.charm._patroni.render_file(f"{PGBACKREST_CONF_PATH}/pgbackrest.conf", rendered, 0o644)
@@ -866,6 +867,7 @@ def _retrieve_s3_parameters(self) -> Tuple[Dict, List[str]]:
         s3_parameters.setdefault("region")
         s3_parameters.setdefault("path", "")
         s3_parameters.setdefault("s3-uri-style", "host")
+        s3_parameters.setdefault("delete-older-than-days", "9999999")
 
         # Strip whitespaces from all parameters.
         for key, value in s3_parameters.items():
diff --git a/templates/pgbackrest.conf.j2 b/templates/pgbackrest.conf.j2
index 3c2d023ba4..fcd7dea00c 100644
--- a/templates/pgbackrest.conf.j2
+++ b/templates/pgbackrest.conf.j2
@@ -2,7 +2,8 @@
 backup-standby=y
 lock-path=/tmp
 log-path={{ log_path }}
-repo1-retention-full=9999999
+repo1-retention-full-type=time
+repo1-retention-full={{ retention_full }}
 repo1-type=s3
 repo1-path={{ path }}
 repo1-s3-region={{ region }}
diff --git a/tests/unit/test_backups.py b/tests/unit/test_backups.py
index cc1a0fc25d..06229f7cdb 100644
--- a/tests/unit/test_backups.py
+++ b/tests/unit/test_backups.py
@@ -1453,6 +1453,7 @@ def test_render_pgbackrest_conf_file(harness):
                 "path": "test-path/",
                 "region": "us-east-1",
                 "s3-uri-style": "path",
+                "delete-older-than-days": "30",
             },
             [],
         )
@@ -1476,6 +1477,7 @@ def test_render_pgbackrest_conf_file(harness):
             stanza=harness.charm.backup.stanza_name,
             storage_path=harness.charm._storage_path,
             user="backup",
+            retention_full=30,
         )
 
         # Patch the `open` method with our mock.
@@ -1539,6 +1541,7 @@ def test_retrieve_s3_parameters(harness):
                 {
                     "access-key": "test-access-key",
                     "bucket": "test-bucket",
+                    "delete-older-than-days": "9999999",
                     "endpoint": "https://s3.amazonaws.com",
                     "path": "/",
                     "region": None,
@@ -1558,6 +1561,7 @@ def test_retrieve_s3_parameters(harness):
             "path": " test-path/ ",
             "region": " us-east-1 ",
             "s3-uri-style": " path ",
+            "delete-older-than-days": "30",
         }
         tc.assertEqual(
             harness.charm.backup._retrieve_s3_parameters(),
@@ -1570,6 +1574,7 @@ def test_retrieve_s3_parameters(harness):
                     "region": "us-east-1",
                     "s3-uri-style": "path",
                     "secret-key": "test-secret-key",
+                    "delete-older-than-days": "30",
                 },
                 [],
             ),