1. when the water level is below the "Low" Sensor, the pump should run and pump water into the tank
2. the pump should continue to run even after the water level has increased over "Low" Sensor
3. When the water level reach the "high" Sensor the Pump should stop.
4. the pump should not start again till the water level is below the "Low" Sensor

In order to achieve the above, we will require two sensor in the water tank, for this project we will use "Cable Float Sensor" and a "Contactor". Its a simple project without any electronic components.

The use of dual sensor will allow for a hysteresis for the pump control an will prevent the pump from oscillating  ON / OFF due to any turbulence or sensor issues, hence provide a fall back safety system for the pump control in a automatic system. Although we strongly recommend Dual Sensor, many of our clients have use a single sensor.