diff --git a/manifests/hub.yaml b/manifests/hub.yaml
index 214bbcf..cf72f76 100644
--- a/manifests/hub.yaml
+++ b/manifests/hub.yaml
@@ -80,6 +80,7 @@ data:
       prune_schedule: "04:30"
     alerting:
       stale_threshold: "30m"
+      storage_fill_warn_percent: 20
     notifications:
       # Resend API key is NOT stored here. It is injected at runtime from Secret/resend-api
       # via the RESEND_API_KEY env var (see Deployment below). The Secret is created out-of-band