diff --git a/platformio.ini b/platformio.ini
index 0c55a85..02ecd40 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -16,4 +16,5 @@ framework = arduino
 monitor_speed = 115200
 
 lib_deps =
-    https://github.com/milesburton/Arduino-Temperature-Control-Library/
\ No newline at end of file
+    https://github.com/milesburton/Arduino-Temperature-Control-Library/
+    d03n3rfr1tz3/HC-SR04@^1.1.2
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index 485b09a..eb46c13 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -44,7 +44,15 @@ float tempC_air;
 float tempCmean_air[TEMPMEAN_SIZE];
 
 
-    
+// ######## Water Level
+#include <HCSR04.h>
+#define HCSR04_PIN_ECHO 17
+#define HCSR04_PIN_TRIGGER 16
+#define READINTERVAL_HCSR04 100
+
+#define WATERLEVELMEAN_SIZE 32
+float waterlevelMean[WATERLEVELMEAN_SIZE];
+uint16_t waterlevelMean_pos=0;
 
 
 unsigned long last_print=0;
@@ -55,8 +63,8 @@ float getMean(uint16_t *parray,uint16_t psize);
 float getMeanf(float *parray,uint16_t psize);
 uint16_t getMin(uint16_t *parray, uint16_t psize);
 uint16_t getMax(uint16_t *parray, uint16_t psize);
-bool isTempArrayOK(uint16_t *parray,uint16_t psize, uint16_t pcheck);
-bool isTempArrayOKf(float *parray,uint16_t psize, float pcheck);
+bool isValueArrayOK(uint16_t *parray,uint16_t psize, uint16_t pcheck);
+bool isValueArrayOKf(float *parray,uint16_t psize, float pcheck);
 
 
 void printAddress(DeviceAddress deviceAddress);
@@ -75,6 +83,8 @@ void setup() {
   ledcAttachPin(EC_PIN_FREQ, EC_PWM_CH);
   ledcWrite(EC_PWM_CH, 127);
 
+  HCSR04.begin(HCSR04_PIN_TRIGGER, HCSR04_PIN_ECHO);
+
   //initialize mean array
   for (uint16_t i=0;i<TEMPMEAN_SIZE;i++) {
     tempCmean_reservoir[i]=-127;
@@ -126,6 +136,8 @@ void loop() {
 
   bool flag_print=false;
 
+  
+
   if (loopmillis>last_read_ec+EC_READ_INTERVAL) {
     last_read_ec=loopmillis;
     ec_array_pos++;
@@ -135,6 +147,7 @@ void loop() {
 
     //Serial.print(ec_array[ec_array_pos]); Serial.print(" ");
   }
+
   
   static unsigned long last_read_ds18b20;
   static bool flag_requestTemperatures=false;
@@ -144,7 +157,7 @@ void loop() {
       flag_requestTemperatures=false;
     }
     if (!flag_requestTemperatures) {
-      sensors.requestTemperatures();
+      sensors.requestTemperatures(); //this takes ~600ms
       flag_requestTemperatures=true;
     }
     if (sensors.isConversionComplete()) {
@@ -171,9 +184,28 @@ void loop() {
       tempCmean_pos%=TEMPMEAN_SIZE;
     }
     
-    
   }
 
+  
+
+
+  static unsigned long last_read_hcsr04;
+  if (loopmillis>=last_read_hcsr04+READINTERVAL_HCSR04) {
+    last_read_hcsr04=loopmillis;
+    float temperature=20.0;
+    if (tempC_air!=DEVICE_DISCONNECTED_C && isValueArrayOKf(tempCmean_air,TEMPMEAN_SIZE,DEVICE_DISCONNECTED_C)) { //sensor ok
+      temperature=getMeanf(tempCmean_air,TEMPMEAN_SIZE);
+    }
+    
+    
+    double* distances = HCSR04.measureDistanceMm(temperature);
+
+    waterlevelMean[waterlevelMean_pos]=distances[0];
+    waterlevelMean_pos++;
+    waterlevelMean_pos%=WATERLEVELMEAN_SIZE;
+  }
+
+  
   if (loopmillis>last_print+500) { 
     last_print=loopmillis;
 
@@ -181,11 +213,19 @@ void loop() {
     Serial.print(getMean(ec_array,EC_ARRAY_SIZE),3);
     Serial.print("\t spread="); Serial.print(getMax(ec_array,EC_ARRAY_SIZE) - getMin(ec_array,EC_ARRAY_SIZE)); 
 
-    if (isTempArrayOKf(tempCmean_reservoir,TEMPMEAN_SIZE,DEVICE_DISCONNECTED_C)){
+    if (isValueArrayOKf(tempCmean_reservoir,TEMPMEAN_SIZE,DEVICE_DISCONNECTED_C)){
       Serial.print("\t Treservoir="); Serial.print(getMeanf(tempCmean_reservoir,TEMPMEAN_SIZE)); Serial.print("\t Tair="); Serial.print(getMeanf(tempCmean_air,TEMPMEAN_SIZE));
     }else{
-      Serial.print("\t waiting for temperature array");
+      Serial.print("\t waiting for temperature");
     }
+
+    
+    if (isValueArrayOKf(waterlevelMean,WATERLEVELMEAN_SIZE,0)){
+      Serial.print("\t Dist="); Serial.print(getMeanf(waterlevelMean,WATERLEVELMEAN_SIZE));  Serial.print("mm");
+    }else{
+      Serial.print("\t waiting for distance");
+    }
+    
     
 
     Serial.println();   
@@ -211,7 +251,7 @@ float getMeanf(float *parray,uint16_t psize) {
   return mean/psize;
 }
 
-bool isTempArrayOK(uint16_t *parray,uint16_t psize, uint16_t pcheck) { //check if array has error values
+bool isValueArrayOK(uint16_t *parray,uint16_t psize, uint16_t pcheck) { //check if array has error values
   for (uint16_t i=0;i<psize;i++) {
     if (parray[i]==pcheck){
       return false;
@@ -219,7 +259,7 @@ bool isTempArrayOK(uint16_t *parray,uint16_t psize, uint16_t pcheck) { //check i
   }
   return true;
 }
-bool isTempArrayOKf(float *parray,uint16_t psize, float pcheck) { //check if array has error values
+bool isValueArrayOKf(float *parray,uint16_t psize, float pcheck) { //check if array has error values
   for (uint16_t i=0;i<psize;i++) {
     if (parray[i]==pcheck){
       return false;