diff --git a/homeassistant/components/miflora/sensor.py b/homeassistant/components/miflora/sensor.py
index b8073f16d92..61db00fa148 100644
--- a/homeassistant/components/miflora/sensor.py
+++ b/homeassistant/components/miflora/sensor.py
@@ -18,6 +18,7 @@ from homeassistant.const import (
     EVENT_HOMEASSISTANT_START,
     TEMP_CELSIUS,
     TEMP_FAHRENHEIT,
+    UNIT_CONDUCTIVITY,
     UNIT_PERCENTAGE,
 )
 from homeassistant.core import callback
@@ -54,7 +55,7 @@ SENSOR_TYPES = {
     "temperature": ["Temperature", TEMP_CELSIUS, "mdi:thermometer"],
     "light": ["Light intensity", "lx", "mdi:white-balance-sunny"],
     "moisture": ["Moisture", UNIT_PERCENTAGE, "mdi:water-percent"],
-    "conductivity": ["Conductivity", "µS/cm", "mdi:flash-circle"],
+    "conductivity": ["Conductivity", UNIT_CONDUCTIVITY, "mdi:flash-circle"],
     "battery": ["Battery", UNIT_PERCENTAGE, "mdi:battery-charging"],
 }
 
diff --git a/homeassistant/components/mysensors/sensor.py b/homeassistant/components/mysensors/sensor.py
index ac16198ee69..e528d7c4baa 100644
--- a/homeassistant/components/mysensors/sensor.py
+++ b/homeassistant/components/mysensors/sensor.py
@@ -7,6 +7,7 @@ from homeassistant.const import (
     POWER_WATT,
     TEMP_CELSIUS,
     TEMP_FAHRENHEIT,
+    UNIT_CONDUCTIVITY,
     UNIT_DEGREE,
     UNIT_PERCENTAGE,
     UNIT_VOLT,
@@ -41,7 +42,7 @@ SENSORS = {
     "V_CURRENT": ["A", "mdi:flash-auto"],
     "V_PH": ["pH", None],
     "V_ORP": ["mV", None],
-    "V_EC": ["μS/cm", None],
+    "V_EC": [UNIT_CONDUCTIVITY, None],
     "V_VAR": ["var", None],
     "V_VA": ["VA", None],
 }
diff --git a/homeassistant/components/plant/__init__.py b/homeassistant/components/plant/__init__.py
index 3e35559bb62..f63df3995ec 100644
--- a/homeassistant/components/plant/__init__.py
+++ b/homeassistant/components/plant/__init__.py
@@ -16,6 +16,7 @@ from homeassistant.const import (
     STATE_UNAVAILABLE,
     STATE_UNKNOWN,
     TEMP_CELSIUS,
+    UNIT_CONDUCTIVITY,
     UNIT_PERCENTAGE,
 )
 from homeassistant.core import callback
@@ -147,7 +148,7 @@ class Plant(Entity):
             "max": CONF_MAX_MOISTURE,
         },
         READING_CONDUCTIVITY: {
-            ATTR_UNIT_OF_MEASUREMENT: "µS/cm",
+            ATTR_UNIT_OF_MEASUREMENT: UNIT_CONDUCTIVITY,
             "min": CONF_MIN_CONDUCTIVITY,
             "max": CONF_MAX_CONDUCTIVITY,
         },
diff --git a/homeassistant/const.py b/homeassistant/const.py
index 99274d59ff7..74647864fab 100644
--- a/homeassistant/const.py
+++ b/homeassistant/const.py
@@ -409,6 +409,9 @@ MASS_MICROGRAMS = "µg"
 MASS_OUNCES: str = "oz"
 MASS_POUNDS: str = "lb"
 
+# Conductivity units
+UNIT_CONDUCTIVITY: str = f"µS/{LENGTH_CENTIMETERS}"
+
 # UV Index units
 UNIT_UV_INDEX: str = "UV index"
 
diff --git a/tests/components/plant/test_init.py b/tests/components/plant/test_init.py
index 5250fb0fa70..0f8cac370e8 100644
--- a/tests/components/plant/test_init.py
+++ b/tests/components/plant/test_init.py
@@ -13,6 +13,7 @@ from homeassistant.const import (
     STATE_PROBLEM,
     STATE_UNAVAILABLE,
     STATE_UNKNOWN,
+    UNIT_CONDUCTIVITY,
 )
 from homeassistant.setup import setup_component
 
@@ -93,7 +94,9 @@ class TestPlant(unittest.TestCase):
 
     def test_initial_states(self):
         """Test plant initialises attributes if sensor already exists."""
-        self.hass.states.set(MOISTURE_ENTITY, 5, {ATTR_UNIT_OF_MEASUREMENT: "us/cm"})
+        self.hass.states.set(
+            MOISTURE_ENTITY, 5, {ATTR_UNIT_OF_MEASUREMENT: UNIT_CONDUCTIVITY}
+        )
         plant_name = "some_plant"
         assert setup_component(
             self.hass, plant.DOMAIN, {plant.DOMAIN: {plant_name: GOOD_CONFIG}}
@@ -111,7 +114,9 @@ class TestPlant(unittest.TestCase):
         assert setup_component(
             self.hass, plant.DOMAIN, {plant.DOMAIN: {plant_name: GOOD_CONFIG}}
         )
-        self.hass.states.set(MOISTURE_ENTITY, 5, {ATTR_UNIT_OF_MEASUREMENT: "us/cm"})
+        self.hass.states.set(
+            MOISTURE_ENTITY, 5, {ATTR_UNIT_OF_MEASUREMENT: UNIT_CONDUCTIVITY}
+        )
         self.hass.block_till_done()
         state = self.hass.states.get(f"plant.{plant_name}")
         assert STATE_PROBLEM == state.state
@@ -127,7 +132,9 @@ class TestPlant(unittest.TestCase):
             self.hass, plant.DOMAIN, {plant.DOMAIN: {plant_name: GOOD_CONFIG}}
         )
         self.hass.states.set(
-            MOISTURE_ENTITY, STATE_UNAVAILABLE, {ATTR_UNIT_OF_MEASUREMENT: "us/cm"}
+            MOISTURE_ENTITY,
+            STATE_UNAVAILABLE,
+            {ATTR_UNIT_OF_MEASUREMENT: UNIT_CONDUCTIVITY},
         )
         self.hass.block_till_done()
         state = self.hass.states.get(f"plant.{plant_name}")
@@ -143,13 +150,17 @@ class TestPlant(unittest.TestCase):
         assert setup_component(
             self.hass, plant.DOMAIN, {plant.DOMAIN: {plant_name: GOOD_CONFIG}}
         )
-        self.hass.states.set(MOISTURE_ENTITY, 42, {ATTR_UNIT_OF_MEASUREMENT: "us/cm"})
+        self.hass.states.set(
+            MOISTURE_ENTITY, 42, {ATTR_UNIT_OF_MEASUREMENT: UNIT_CONDUCTIVITY}
+        )
         self.hass.block_till_done()
         state = self.hass.states.get(f"plant.{plant_name}")
         assert state.state == STATE_OK
         assert state.attributes[plant.READING_MOISTURE] == 42
         self.hass.states.set(
-            MOISTURE_ENTITY, STATE_UNAVAILABLE, {ATTR_UNIT_OF_MEASUREMENT: "us/cm"}
+            MOISTURE_ENTITY,
+            STATE_UNAVAILABLE,
+            {ATTR_UNIT_OF_MEASUREMENT: UNIT_CONDUCTIVITY},
         )
         self.hass.block_till_done()
         state = self.hass.states.get(f"plant.{plant_name}")