extend wire of the sensor


i would like to know how to extend the sensor wires connected to and arduino without affecting the signal
ie water tank level sensing(ultrasonic sensor) to monitoring station(display) is about 30ft

Put a second Arduino to the sensor and connect the two by some communication channel. Which to choose depends on the environment, RS485 is always a good choice for such situations but you may have other preferences.

an ultrasonic sensor is no problem as it works on digital signals.

thanks for the reply!