int echoPin=2;
int trigPin =3;
int LedGreen =8;
int LedRed =9;
long duration;
int distance;
void setup()
 {
pinMode(trigPin,OUTPUT);
pinMode(echoPin,INPUT);
pinMode(LedGreen,OUTPUT);
pinMode(LedRed,OUTPUT);
Serial.begin(9600);
 }
void loop()
 {
digitalWrite(trigPin,LOW);
delay(2);// or delayMicroseconds(2);

digitalWrite(trigPin,HIGH);
delay(10);// or delayMicroseconds(10);
digitalWrite(trigPin,LOW);
duration=pulseIn(echoPin,HIGH);
distance=(duration*0.034/2);
Serial.print("Distance : " );
Serial.print(distance);
Serial.println(" cm ");
if(distance <20)
{
digitalWrite(LedRed, HIGH);
Serial.print("Water Levelis below 20%" );
}
else if(distance >90)
{
digitalWrite(LedGreen, HIGH);
Serial.print("Water Levelis above 90%" );
}
else
{
digitalWrite(LedGreen, LOW);
digitalWrite(LedRed, LOW);
}
 }