Abstract: A ground water alert device includes an elongated water proof cable member which has a predetermined length and is inserted into a water level monitoring pipe of a well for a predetermined depth above a water table, a cable housing for delivering and collecting the cable member, a water sensor such as a probe which is electrically connected to a free end of the cable member for lowering into the monitoring pipe to the predetermined depth above the water table, a DC power source, a control circuitry electrically connected between the DC power source and the cable member for generating alert signals when the water sensor detects water, a depth indicator having a plurality of length scales uniformly provided along the cable member to indicate the length of the cable member from the water sensor, and a cable supporter for securing the cable member in place at a top end of the monitoring pipe so as to ensure the predetermined length of the cable member retaining in the monitoring pipe.