diff --git a/CHANGELOG.md b/CHANGELOG.md
index f3d2e14968..4b993c3e11 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -98,6 +98,7 @@
 * [BUGFIX] Alerts: Fix autoscaling metrics joins in `MimirAutoscalerNotActive` when series churn. #9412
 * [BUGFIX] Alerts: Exclude failed cache "add" operations from alerting since failures are expected in normal operation. #9658
 * [BUGFIX] Alerts: Exclude read-only replicas from `IngesterInstanceHasNoTenants` alert. #9843
+* [BUGFIX] Alerts: Use resident set memory for the `EtcdAllocatingTooMuchMemory` alert so that ephemeral file cache memory doesn't cause the alert to misfire. #9997
 
 ### Jsonnet
 
diff --git a/operations/helm/tests/metamonitoring-values-generated/mimir-distributed/templates/metamonitoring/mixin-alerts.yaml b/operations/helm/tests/metamonitoring-values-generated/mimir-distributed/templates/metamonitoring/mixin-alerts.yaml
index 929e6927b5..8f5d18333d 100644
--- a/operations/helm/tests/metamonitoring-values-generated/mimir-distributed/templates/metamonitoring/mixin-alerts.yaml
+++ b/operations/helm/tests/metamonitoring-values-generated/mimir-distributed/templates/metamonitoring/mixin-alerts.yaml
@@ -605,7 +605,7 @@ spec:
               runbook_url: https://grafana.com/docs/mimir/latest/operators-guide/mimir-runbooks/#etcdallocatingtoomuchmemory
             expr: |
               (
-                container_memory_working_set_bytes{container="etcd"}
+                container_memory_rss{container="etcd"}
                   /
                 ( container_spec_memory_limit_bytes{container="etcd"} > 0 )
               ) > 0.65
@@ -619,7 +619,7 @@ spec:
               runbook_url: https://grafana.com/docs/mimir/latest/operators-guide/mimir-runbooks/#etcdallocatingtoomuchmemory
             expr: |
               (
-                container_memory_working_set_bytes{container="etcd"}
+                container_memory_rss{container="etcd"}
                   /
                 ( container_spec_memory_limit_bytes{container="etcd"} > 0 )
               ) > 0.8
diff --git a/operations/mimir-mixin-compiled-baremetal/alerts.yaml b/operations/mimir-mixin-compiled-baremetal/alerts.yaml
index 9283e7e8ee..d4776cf7c2 100644
--- a/operations/mimir-mixin-compiled-baremetal/alerts.yaml
+++ b/operations/mimir-mixin-compiled-baremetal/alerts.yaml
@@ -583,7 +583,7 @@ groups:
             runbook_url: https://grafana.com/docs/mimir/latest/operators-guide/mimir-runbooks/#etcdallocatingtoomuchmemory
           expr: |
             (
-              container_memory_working_set_bytes{container="etcd"}
+              container_memory_rss{container="etcd"}
                 /
               ( container_spec_memory_limit_bytes{container="etcd"} > 0 )
             ) > 0.65
@@ -597,7 +597,7 @@ groups:
             runbook_url: https://grafana.com/docs/mimir/latest/operators-guide/mimir-runbooks/#etcdallocatingtoomuchmemory
           expr: |
             (
-              container_memory_working_set_bytes{container="etcd"}
+              container_memory_rss{container="etcd"}
                 /
               ( container_spec_memory_limit_bytes{container="etcd"} > 0 )
             ) > 0.8
diff --git a/operations/mimir-mixin-compiled/alerts.yaml b/operations/mimir-mixin-compiled/alerts.yaml
index be782a551d..275dd27111 100644
--- a/operations/mimir-mixin-compiled/alerts.yaml
+++ b/operations/mimir-mixin-compiled/alerts.yaml
@@ -593,7 +593,7 @@ groups:
             runbook_url: https://grafana.com/docs/mimir/latest/operators-guide/mimir-runbooks/#etcdallocatingtoomuchmemory
           expr: |
             (
-              container_memory_working_set_bytes{container="etcd"}
+              container_memory_rss{container="etcd"}
                 /
               ( container_spec_memory_limit_bytes{container="etcd"} > 0 )
             ) > 0.65
@@ -607,7 +607,7 @@ groups:
             runbook_url: https://grafana.com/docs/mimir/latest/operators-guide/mimir-runbooks/#etcdallocatingtoomuchmemory
           expr: |
             (
-              container_memory_working_set_bytes{container="etcd"}
+              container_memory_rss{container="etcd"}
                 /
               ( container_spec_memory_limit_bytes{container="etcd"} > 0 )
             ) > 0.8
diff --git a/operations/mimir-mixin/alerts/alerts.libsonnet b/operations/mimir-mixin/alerts/alerts.libsonnet
index f66af7829a..75c7e1ca78 100644
--- a/operations/mimir-mixin/alerts/alerts.libsonnet
+++ b/operations/mimir-mixin/alerts/alerts.libsonnet
@@ -875,7 +875,7 @@ local utils = import 'mixin-utils/utils.libsonnet';
           alert: 'EtcdAllocatingTooMuchMemory',
           expr: |||
             (
-              container_memory_working_set_bytes{container="etcd"}
+              container_memory_rss{container="etcd"}
                 /
               ( container_spec_memory_limit_bytes{container="etcd"} > 0 )
             ) > 0.65
@@ -894,7 +894,7 @@ local utils = import 'mixin-utils/utils.libsonnet';
           alert: 'EtcdAllocatingTooMuchMemory',
           expr: |||
             (
-              container_memory_working_set_bytes{container="etcd"}
+              container_memory_rss{container="etcd"}
                 /
               ( container_spec_memory_limit_bytes{container="etcd"} > 0 )
             ) > 0.8