diff --git a/monitoring/mongodb/alerts.test.yaml b/monitoring/mongodb/alerts.test.yaml
index 8d41031996..c779720ee1 100644
--- a/monitoring/mongodb/alerts.test.yaml
+++ b/monitoring/mongodb/alerts.test.yaml
@@ -670,4 +670,46 @@ tests:
                 MongoDB replica set `data-db-mongodb-sharded-shard-1` is not in the expected state.
                 It does not have the expected number of SECONDARY members. Please ensure that all
                 instances are running properly.
-              summary: MongoDB replica set out of sync
\ No newline at end of file
+              summary: MongoDB replica set out of sync
+
+  - name: MongoDbCompactionNeeded
+    interval: 5m
+    input_series:
+      # Compaction-needed DB: 80% disk usage, 40% free ratio, 12 GB free (>10 GiB)
+      - series: mongodb_dbstats_fsUsedSize{namespace="zenko", pod="data-db-mongodb-sharded-shard0-data-0", database="needs-compaction"}
+        values: 8e9x13
+      - series: mongodb_dbstats_fsTotalSize{namespace="zenko", pod="data-db-mongodb-sharded-shard0-data-0", database="needs-compaction"}
+        values: 1e10x13
+      - series: mongodb_dbstats_totalFreeStorageSize{namespace="zenko", pod="data-db-mongodb-sharded-shard0-data-0", database="needs-compaction"}
+        values: 12e9x13
+      - series: mongodb_dbstats_totalSize{namespace="zenko", pod="data-db-mongodb-sharded-shard0-data-0", database="needs-compaction"}
+        values: 30e9x13
+      # Healthy DB on same pod: same 80% disk usage but only 1 GB free (below both ratio and absolute thresholds)
+      - series: mongodb_dbstats_fsUsedSize{namespace="zenko", pod="data-db-mongodb-sharded-shard0-data-0", database="healthy-db"}
+        values: 8e9x13
+      - series: mongodb_dbstats_fsTotalSize{namespace="zenko", pod="data-db-mongodb-sharded-shard0-data-0", database="healthy-db"}
+        values: 1e10x13
+      - series: mongodb_dbstats_totalFreeStorageSize{namespace="zenko", pod="data-db-mongodb-sharded-shard0-data-0", database="healthy-db"}
+        values: 1e9x13
+      - series: mongodb_dbstats_totalSize{namespace="zenko", pod="data-db-mongodb-sharded-shard0-data-0", database="healthy-db"}
+        values: 30e9x13
+    alert_rule_test:
+      # for: 1h not yet satisfied
+      - alertname: MongoDbCompactionNeeded
+        eval_time: 10m
+        exp_alerts: []
+      - alertname: MongoDbCompactionNeeded
+        eval_time: 55m
+        exp_alerts: []
+      # for: 1h satisfied; only the needs-compaction DB fires
+      - alertname: MongoDbCompactionNeeded
+        eval_time: 65m
+        exp_alerts:
+          - exp_labels:
+              severity: warning
+              namespace: zenko
+              pod: data-db-mongodb-sharded-shard0-data-0
+              database: needs-compaction
+            exp_annotations:
+              description: "MongoDB pod `data-db-mongodb-sharded-shard0-data-0` database `needs-compaction` has accumulated significant reclaimable storage while the underlying filesystem is filling up. Consider running compaction to recover disk space."
+              summary: MongoDB compaction needed
diff --git a/monitoring/mongodb/alerts.yaml b/monitoring/mongodb/alerts.yaml
index 6e272d25ec..ac09c4e8fb 100644
--- a/monitoring/mongodb/alerts.yaml
+++ b/monitoring/mongodb/alerts.yaml
@@ -27,6 +27,15 @@ x-inputs:
   - name: replicationLagOplogSizeThreshold
     type: config
     value: 0.5
+  - name: compactionDiskUsageThreshold
+    type: config
+    value: 0.7
+  - name: compactionFreeStorageRatioThreshold
+    type: config
+    value: 0.3
+  - name: compactionFreeStorageAbsoluteThreshold
+    type: config
+    value: 10 * 1024 * 1024 * 1024 # 10 GiB, in bytes
 
 groups:
 - name: MongoDb
@@ -270,6 +279,27 @@ groups:
       description: "MongoDB pod `{{ $labels.pod }}` has been in the 'STARTUP2' state for more than 1 hour. Please ensure that the instance is running properly."
       summary: MongoDB node in STARTUP2 state for too long
 
+  - alert: MongoDbCompactionNeeded
+    expr: |
+      (
+        mongodb_dbstats_fsUsedSize{namespace="${namespace}",pod=~"${service}.*"}
+          / mongodb_dbstats_fsTotalSize{namespace="${namespace}",pod=~"${service}.*"}
+      ) > ${compactionDiskUsageThreshold}
+      and
+      (
+        mongodb_dbstats_totalFreeStorageSize{namespace="${namespace}",pod=~"${service}.*"}
+          / mongodb_dbstats_totalSize{namespace="${namespace}",pod=~"${service}.*"}
+      ) > ${compactionFreeStorageRatioThreshold}
+      and
+      mongodb_dbstats_totalFreeStorageSize{namespace="${namespace}",pod=~"${service}.*"}
+        > ${compactionFreeStorageAbsoluteThreshold}
+    for: 1h
+    labels:
+      severity: warning
+    annotations:
+      description: "MongoDB pod `{{ $labels.pod }}` database `{{ $labels.database }}` has accumulated significant reclaimable storage while the underlying filesystem is filling up. Consider running compaction to recover disk space."
+      summary: MongoDB compaction needed
+
   - alert: MongoDbRSNotSynced
     expr: |
       count by (rs_nm, statefulset) (
diff --git a/solution-base/mongodb/charts/mongodb-sharded/values.yaml b/solution-base/mongodb/charts/mongodb-sharded/values.yaml
index 0aa3089c79..cfdfc9a2f6 100644
--- a/solution-base/mongodb/charts/mongodb-sharded/values.yaml
+++ b/solution-base/mongodb/charts/mongodb-sharded/values.yaml
@@ -1815,7 +1815,7 @@ metrics:
   ## @param metrics.extraArgs String with extra arguments to the metrics exporter
   ## ref: https://github.com/percona/mongodb_exporter/blob/main/main.go
   ##
-  extraArgs: "--collector.diagnosticdata --collector.replicasetstatus --collector.dbstats --collector.topmetrics --compatible-mode"
+  extraArgs: "--collector.diagnosticdata --collector.replicasetstatus --collector.dbstats --collector.dbstatsfreestorage --collector.topmetrics --compatible-mode"
   ## @param metrics.resourcesPreset Set container resources according to one common preset (allowed values: none, nano, micro, small, medium, large, xlarge, 2xlarge). This is ignored if metrics.resources is set (metrics.resources is recommended for production).
   ## More information: https://github.com/bitnami/charts/blob/main/bitnami/common/templates/_resources.tpl#L15
   ##