A flood sensor for automation systems comprising at least two electrodes connected with a measuring circuit arranged to detect a plurality of liquid levels; and wherein the measuring circuit has a zero static current consumption, having current flow only in the presence of fluid; and wherein if a liquid is detected, the output of the circuit is activated and a microcontroller leaves a zero-power state in which it normally stays; and wherein the microcontroller comprises a program or programs stored in a memory and configured for being run by means of the microcontroller, wherein said programs comprise instructions for: (a) measuring the impedance of the liquid that has activated the output of the measuring circuit; and (b) sending the measured impedance to a central control.