Simple Sensor and Detector Liquids

This is a very simple liquid detector which controls a relay, this gives you the option to be used for hundreds of applications. You can use it as a float switch to turn on the water pump alarm, rain, etc..

Sensor and Detector Liquids Circuit Diagram:

 
He uses a 4093 IC and transistor can be anyone, provided that it meets the power relay. This sensor can be used with Arduino no problem.