diff --git a/Dockerfile b/Dockerfile
index c9dbad0..61bfa80 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -6,5 +6,6 @@ ADD watch /watch
 
 VOLUME /data
 
+ENV S3_SYNC_FLAGS "--delete"
 ENTRYPOINT [ "./watch" ]
 CMD ["/data"]
diff --git a/README.md b/README.md
index 6275e72..bc60d95 100644
--- a/README.md
+++ b/README.md
@@ -80,6 +80,9 @@ docker run -d --name my-data-container \
            elementar/s3-volume --force-restore /data s3://mybucket/someprefix
 ```
 
+### Deletion and sync
+By default if there are files that are deleted in your local file system, those will be deleted remotely.   If you wish to turn this off set the environment variable S3_SYNC_FLAGS=":
+
 ### Using Compose and named volumes
 
 Most of the time, you will use this image to sync data for another container.
diff --git a/watch b/watch
index a9afcab..33dee7a 100755
--- a/watch
+++ b/watch
@@ -61,7 +61,7 @@ function restore {
 
 function backup {
   echo "backup $LOCAL => $REMOTE"
-  if ! $AWS s3 sync "$LOCAL" "$REMOTE" --delete; then
+  if ! $AWS s3 sync "$LOCAL" "$REMOTE" $S3_SYNC_FLAGS; then
     echo "backup failed" 1>&2
     return 1
   fi
@@ -69,7 +69,7 @@ function backup {
 
 function final_backup {
   echo "backup $LOCAL => $REMOTE"
-  while ! $AWS s3 sync "$LOCAL" "$REMOTE" --delete; do
+  while ! $AWS s3 sync "$LOCAL" "$REMOTE" $S3_SYNC_FLAGS; do
     echo "backup failed, will retry" 1>&2
     sleep 1
   done