diff --git a/homeassistant/components/geonetnz_volcano/__init__.py b/homeassistant/components/geonetnz_volcano/__init__.py
index e4bf2d2cb8c..da081b42599 100644
--- a/homeassistant/components/geonetnz_volcano/__init__.py
+++ b/homeassistant/components/geonetnz_volcano/__init__.py
@@ -14,7 +14,6 @@ from homeassistant.const import (
     CONF_RADIUS,
     CONF_SCAN_INTERVAL,
     CONF_UNIT_SYSTEM,
-    CONF_UNIT_SYSTEM_IMPERIAL,
     LENGTH_KILOMETERS,
     LENGTH_MILES,
 )
@@ -26,7 +25,14 @@ from homeassistant.helpers.typing import ConfigType
 from homeassistant.util.unit_conversion import DistanceConverter
 
 from .config_flow import configured_instances
-from .const import DEFAULT_RADIUS, DEFAULT_SCAN_INTERVAL, DOMAIN, FEED, PLATFORMS
+from .const import (
+    DEFAULT_RADIUS,
+    DEFAULT_SCAN_INTERVAL,
+    DOMAIN,
+    FEED,
+    IMPERIAL_UNITS,
+    PLATFORMS,
+)
 
 _LOGGER = logging.getLogger(__name__)
 
@@ -85,7 +91,7 @@ async def async_setup_entry(hass: HomeAssistant, config_entry: ConfigEntry) -> b
 
     radius = config_entry.data[CONF_RADIUS]
     unit_system = config_entry.data[CONF_UNIT_SYSTEM]
-    if unit_system == CONF_UNIT_SYSTEM_IMPERIAL:
+    if unit_system == IMPERIAL_UNITS:
         radius = DistanceConverter.convert(radius, LENGTH_MILES, LENGTH_KILOMETERS)
     # Create feed entity manager for all platforms.
     manager = GeonetnzVolcanoFeedEntityManager(hass, config_entry, radius, unit_system)
diff --git a/homeassistant/components/geonetnz_volcano/config_flow.py b/homeassistant/components/geonetnz_volcano/config_flow.py
index 6de169c8602..d095aefab01 100644
--- a/homeassistant/components/geonetnz_volcano/config_flow.py
+++ b/homeassistant/components/geonetnz_volcano/config_flow.py
@@ -8,14 +8,18 @@ from homeassistant.const import (
     CONF_RADIUS,
     CONF_SCAN_INTERVAL,
     CONF_UNIT_SYSTEM,
-    CONF_UNIT_SYSTEM_IMPERIAL,
-    CONF_UNIT_SYSTEM_METRIC,
 )
 from homeassistant.core import callback
 from homeassistant.helpers import config_validation as cv
 from homeassistant.util.unit_system import IMPERIAL_SYSTEM
 
-from .const import DEFAULT_RADIUS, DEFAULT_SCAN_INTERVAL, DOMAIN
+from .const import (
+    DEFAULT_RADIUS,
+    DEFAULT_SCAN_INTERVAL,
+    DOMAIN,
+    IMPERIAL_UNITS,
+    METRIC_UNITS,
+)
 
 
 @callback
@@ -59,9 +63,9 @@ class GeonetnzVolcanoFlowHandler(config_entries.ConfigFlow, domain=DOMAIN):
             return await self._show_form({"base": "already_configured"})
 
         if self.hass.config.units is IMPERIAL_SYSTEM:
-            user_input[CONF_UNIT_SYSTEM] = CONF_UNIT_SYSTEM_IMPERIAL
+            user_input[CONF_UNIT_SYSTEM] = IMPERIAL_UNITS
         else:
-            user_input[CONF_UNIT_SYSTEM] = CONF_UNIT_SYSTEM_METRIC
+            user_input[CONF_UNIT_SYSTEM] = METRIC_UNITS
 
         scan_interval = user_input.get(CONF_SCAN_INTERVAL, DEFAULT_SCAN_INTERVAL)
         user_input[CONF_SCAN_INTERVAL] = scan_interval.total_seconds()
diff --git a/homeassistant/components/geonetnz_volcano/const.py b/homeassistant/components/geonetnz_volcano/const.py
index 3a23084aa1f..8c17ff42544 100644
--- a/homeassistant/components/geonetnz_volcano/const.py
+++ b/homeassistant/components/geonetnz_volcano/const.py
@@ -18,3 +18,6 @@ DEFAULT_RADIUS = 50.0
 DEFAULT_SCAN_INTERVAL = timedelta(minutes=5)
 
 PLATFORMS = [Platform.SENSOR]
+
+IMPERIAL_UNITS = "imperial"
+METRIC_UNITS = "metric"
diff --git a/homeassistant/components/geonetnz_volcano/sensor.py b/homeassistant/components/geonetnz_volcano/sensor.py
index 51bca3e467a..e48a4cec0cf 100644
--- a/homeassistant/components/geonetnz_volcano/sensor.py
+++ b/homeassistant/components/geonetnz_volcano/sensor.py
@@ -9,7 +9,6 @@ from homeassistant.const import (
     ATTR_ATTRIBUTION,
     ATTR_LATITUDE,
     ATTR_LONGITUDE,
-    CONF_UNIT_SYSTEM_IMPERIAL,
     LENGTH_KILOMETERS,
     LENGTH_MILES,
 )
@@ -27,6 +26,7 @@ from .const import (
     DEFAULT_ICON,
     DOMAIN,
     FEED,
+    IMPERIAL_UNITS,
 )
 
 _LOGGER = logging.getLogger(__name__)
@@ -113,7 +113,7 @@ class GeonetnzVolcanoSensor(SensorEntity):
         """Update the internal state from the provided feed entry."""
         self._title = feed_entry.title
         # Convert distance if not metric system.
-        if self._unit_system == CONF_UNIT_SYSTEM_IMPERIAL:
+        if self._unit_system == IMPERIAL_UNITS:
             self._distance = round(
                 DistanceConverter.convert(
                     feed_entry.distance_to_home, LENGTH_KILOMETERS, LENGTH_MILES