diff --git a/libnymea/interfaces/interfaces.qrc b/libnymea/interfaces/interfaces.qrc
index d2996531..40554edf 100644
--- a/libnymea/interfaces/interfaces.qrc
+++ b/libnymea/interfaces/interfaces.qrc
@@ -34,6 +34,7 @@
         <file>closablesensor.json</file>
         <file>presencesensor.json</file>
         <file>watersensor.json</file>
+        <file>waterlevelsensor.json</file>
         <file>temperaturesensor.json</file>
         <file>humiditysensor.json</file>
         <file>pressuresensor.json</file>
diff --git a/libnymea/interfaces/waterlevelsensor.json b/libnymea/interfaces/waterlevelsensor.json
new file mode 100644
index 00000000..e0f6893a
--- /dev/null
+++ b/libnymea/interfaces/waterlevelsensor.json
@@ -0,0 +1,12 @@
+{
+    "description": "Sensors that can measure water fill levels.",
+    "extends": "sensor",
+    "states": [
+        {
+            "name": "waterLevel",
+            "type": "double",
+            "unit": "Liter",
+            "logged": true
+        }
+    ]
+}
diff --git a/libnymea/typeutils.h b/libnymea/typeutils.h
index a3da3cda..7d6d4c6d 100644
--- a/libnymea/typeutils.h
+++ b/libnymea/typeutils.h
@@ -142,6 +142,7 @@ public:
         UnitNewtonMeter,
         UnitRpm,
         UnitMilligramPerLiter,
+        UnitLiter,
     };
     Q_ENUM(Unit)
 
diff --git a/nymea.pro b/nymea.pro
index 0794868b..d7a63840 100644
--- a/nymea.pro
+++ b/nymea.pro
@@ -5,7 +5,7 @@ NYMEA_VERSION_STRING=$$system('dpkg-parsechangelog | sed -n -e "s/^Version: //p"
 
 # define protocol versions
 JSON_PROTOCOL_VERSION_MAJOR=5
-JSON_PROTOCOL_VERSION_MINOR=7
+JSON_PROTOCOL_VERSION_MINOR=8
 JSON_PROTOCOL_VERSION="$${JSON_PROTOCOL_VERSION_MAJOR}.$${JSON_PROTOCOL_VERSION_MINOR}"
 LIBNYMEA_API_VERSION_MAJOR=7
 LIBNYMEA_API_VERSION_MINOR=2
diff --git a/tests/auto/api.json b/tests/auto/api.json
index 9d6b39ad..cf87b7e3 100644
--- a/tests/auto/api.json
+++ b/tests/auto/api.json
@@ -1,4 +1,4 @@
-5.7
+5.8
 {
     "enums": {
         "BasicType": [
@@ -377,7 +377,8 @@
             "UnitNewton",
             "UnitNewtonMeter",
             "UnitRpm",
-            "UnitMilligramPerLiter"
+            "UnitMilligramPerLiter",
+            "UnitLiter"
         ],
         "UserError": [
             "UserErrorNoError",