int trig=8,Echo=9;
int D,t;
int count=0;

int DistanceMeasurement()
{
  digitalWrite(trig,HIGH);
  delayMicroseconds(10);
  digitalWrite(trig,LOW);
  t=pulseIn(Echo,HIGH);
  D=t/58.77;
  return D;
}

void setup() {
  // put your setup code here, to run once:
   Serial.begin(9600);
   pinMode(trig,OUTPUT);
   pinMode(Echo,INPUT_PULLUP);
}

void loop() {
  // put your main code here, to run repeatedly:
   if(DistanceMeasurement()>=0 && DistanceMeasurement()<=10)
   {
    Serial.println("Water level is 100%");
    delay(500);
   }
   else if(DistanceMeasurement()>10 && DistanceMeasurement()<=20)
   {
    Serial.println("Water level is 80%");
    delay(500);
   }
   else if(DistanceMeasurement()>20 && DistanceMeasurement()<=30)
   {
    Serial.println("Water level is 60%");
    delay(500);
   }
   else if(DistanceMeasurement()>30 && DistanceMeasurement()<=40)
   {
    Serial.println("Water level is 40%");
    delay(500);
   }
   else if(DistanceMeasurement()>40 && DistanceMeasurement()<=50)
   {
    Serial.println("Water level is 20%");
    delay(500);
   }
   else
   {
    Serial.println("Water level is 0%");
    delay(500);
   }
}