diff --git a/homeassistant/util/unit_system.py b/homeassistant/util/unit_system.py
index fcb8c0a4f16..ef5914fc904 100644
--- a/homeassistant/util/unit_system.py
+++ b/homeassistant/util/unit_system.py
@@ -240,6 +240,7 @@ METRIC_SYSTEM = UnitSystem(
         ("distance", UnitOfLength.MILES): UnitOfLength.KILOMETERS,
         ("distance", UnitOfLength.YARDS): UnitOfLength.METERS,
         # Convert non-metric volumes of gas meters
+        ("gas", UnitOfVolume.CENTUM_CUBIC_FEET): UnitOfVolume.CUBIC_METERS,
         ("gas", UnitOfVolume.CUBIC_FEET): UnitOfVolume.CUBIC_METERS,
         # Convert non-metric precipitation
         ("precipitation", UnitOfLength.INCHES): UnitOfLength.MILLIMETERS,
@@ -250,10 +251,12 @@ METRIC_SYSTEM = UnitSystem(
         ("speed", UnitOfSpeed.FEET_PER_SECOND): UnitOfSpeed.KILOMETERS_PER_HOUR,
         ("speed", UnitOfSpeed.MILES_PER_HOUR): UnitOfSpeed.KILOMETERS_PER_HOUR,
         # Convert non-metric volumes
+        ("volume", UnitOfVolume.CENTUM_CUBIC_FEET): UnitOfVolume.CUBIC_METERS,
         ("volume", UnitOfVolume.CUBIC_FEET): UnitOfVolume.CUBIC_METERS,
         ("volume", UnitOfVolume.FLUID_OUNCES): UnitOfVolume.MILLILITERS,
         ("volume", UnitOfVolume.GALLONS): UnitOfVolume.LITERS,
         # Convert non-metric volumes of water meters
+        ("water", UnitOfVolume.CENTUM_CUBIC_FEET): UnitOfVolume.CUBIC_METERS,
         ("water", UnitOfVolume.CUBIC_FEET): UnitOfVolume.CUBIC_METERS,
         ("water", UnitOfVolume.GALLONS): UnitOfVolume.LITERS,
     },
@@ -283,6 +286,7 @@ US_CUSTOMARY_SYSTEM = UnitSystem(
         # Convert non-USCS volumes of gas meters
         ("gas", UnitOfVolume.CUBIC_METERS): UnitOfVolume.CUBIC_FEET,
         # Convert non-USCS precipitation
+        ("precipitation", UnitOfLength.CENTIMETERS): UnitOfLength.INCHES,
         ("precipitation", UnitOfLength.MILLIMETERS): UnitOfLength.INCHES,
         # Convert non-USCS pressure
         ("pressure", UnitOfPressure.MBAR): UnitOfPressure.PSI,
@@ -292,7 +296,7 @@ US_CUSTOMARY_SYSTEM = UnitSystem(
         ("pressure", UnitOfPressure.HPA): UnitOfPressure.PSI,
         ("pressure", UnitOfPressure.KPA): UnitOfPressure.PSI,
         ("pressure", UnitOfPressure.MMHG): UnitOfPressure.INHG,
-        # Convert non-USCS speeds except knots to mph
+        # Convert non-USCS speeds, except knots, to mph
         ("speed", UnitOfSpeed.METERS_PER_SECOND): UnitOfSpeed.MILES_PER_HOUR,
         ("speed", UnitOfSpeed.KILOMETERS_PER_HOUR): UnitOfSpeed.MILES_PER_HOUR,
         # Convert non-USCS volumes