diff --git a/msc_pygeoapi/connector/elasticsearch_.py b/msc_pygeoapi/connector/elasticsearch_.py
index f637473e..a0050005 100644
--- a/msc_pygeoapi/connector/elasticsearch_.py
+++ b/msc_pygeoapi/connector/elasticsearch_.py
@@ -180,17 +180,27 @@ def delete(self, indexes):
 
         return True
 
-    def create_template(self, name, settings):
+    def create_template(self, name, settings, overwrite=False):
         """
         create an Elasticsearch index template
 
         :param name: `str` index template name
         :param settings: `dict` settings dictionnary for index template
+        :param overwrite: `bool` indicating whether to overwrite existing
+                          template
 
         :returns: `bool` of index template creation status
         """
 
-        if not self.Elasticsearch.indices.exists_template(name=name):
+        template_exists = self.Elasticsearch.indices.exists_template(name=name)
+
+        if template_exists and overwrite:
+            self.Elasticsearch.indices.delete_template(name=name)
+            self.Elasticsearch.indices.put_template(name=name, body=settings)
+        elif template_exists:
+            LOGGER.warning(f'Template {name} already exists')
+            return False
+        else:
             self.Elasticsearch.indices.put_template(name=name, body=settings)
 
         return True
diff --git a/msc_pygeoapi/loader/hydrometric_realtime.py b/msc_pygeoapi/loader/hydrometric_realtime.py
index 7b579454..30cbf2f5 100644
--- a/msc_pygeoapi/loader/hydrometric_realtime.py
+++ b/msc_pygeoapi/loader/hydrometric_realtime.py
@@ -41,6 +41,7 @@
 from msc_pygeoapi.util import (
     check_es_indexes_to_delete,
     configure_es_connection,
+    DATETIME_RFC3339_FMT
 )
 
 
@@ -60,7 +61,7 @@
 SETTINGS = {
     'order': 0,
     'version': 1,
-    'index_patterns': [INDEX_BASENAME],
+    'index_patterns': [f'{INDEX_BASENAME}*'],
     'settings': {
         'number_of_shards': 1,
         'number_of_replicas': 0
@@ -98,7 +99,7 @@
                     },
                     'DATETIME': {
                         'type': 'date',
-                        'format': 'strict_date_hour_minute_second||strict_date_optional_time'  # noqa
+                        'format': 'date_time_no_millis||strict_date_optional_time'  # noqa
                     },
                     'DATETIME_LST': {
                         'type': 'date',
@@ -174,7 +175,7 @@ def __init__(self, conn_config={}):
         BaseLoader.__init__(self)
 
         self.conn = ElasticsearchConnector(conn_config)
-        self.conn.create_template(INDEX_BASENAME, SETTINGS)
+        self.conn.create_template(INDEX_BASENAME, SETTINGS, overwrite=True)
 
         self.stations = {}
         self.read_stations_list()
@@ -284,11 +285,10 @@ def generate_observations(self, filepath):
                 try:
                     # Convert timestamp to UTC time.
                     utc_datetime = delocalize_date(date_)
-                    utc_datestamp = utc_datetime.strftime('%Y-%m-%d.%H:%M:%S')
+                    utc_datestamp = utc_datetime.strftime(DATETIME_RFC3339_FMT)
                     # Generate an ID now that all fields are known.
                     observation_id = f'{station}.{utc_datestamp}'
 
-                    utc_datestamp = utc_datestamp.replace('.', 'T')
                 except Exception as err:
                     LOGGER.error(f'Cannot interpret datetime value {date_} in {filepath}'  # noqa
                                  f' due to: {err} (skipping)')