Sir, I want a simple circuit that controls a water pump. Thank you.

 

The simpliest way is to put a floater sw connected to an aux relay. When level is down floater sw activate the relay that controls your motor pump, once the desired level is reached floater sw opens an aux relay opens too leaving the motor without power

 

Use a simple float pump switch switch. You will find a couple of examples here - http://www.anadexlabs.com.au/shop/catalog/Float-Switches-p-1-c-262.html.

Float pump switches are float switches that have speacially been designed to handle switching pumps on and off. These float switches come in "pump up" or "pump down" configurations.

Regards,
Bill