diff --git a/homeassistant/components/water_heater/strings.json b/homeassistant/components/water_heater/strings.json
index c77a1612992..ce5f81e29f8 100644
--- a/homeassistant/components/water_heater/strings.json
+++ b/homeassistant/components/water_heater/strings.json
@@ -101,6 +101,18 @@
         "min_temp": {
           "name": "Min target temperature"
         },
+        "operation_mode": {
+          "name": "Operation mode",
+          "state": {
+            "eco": "[%key:component::water_heater::entity_component::_::state::eco%]",
+            "electric": "[%key:component::water_heater::entity_component::_::state::electric%]",
+            "gas": "[%key:component::water_heater::entity_component::_::state::gas%]",
+            "heat_pump": "[%key:component::water_heater::entity_component::_::state::heat_pump%]",
+            "high_demand": "[%key:component::water_heater::entity_component::_::state::high_demand%]",
+            "off": "[%key:common::state::off%]",
+            "performance": "[%key:component::water_heater::entity_component::_::state::performance%]"
+          }
+        },
         "target_temp_high": {
           "name": "Upper target temperature"
         },