A leak detector for detecting flow of at least partially conductive fluid includes two electrodes and an electrical circuit. A valve device including an actuator is constructed to receive open and close signals for opening and closing the valve device between an input port and an outer port. The two electrodes are located on opposite sides of the valve device and are electrically isolated from each other in absence of the liquid flowing between the input port and the output port. The electrical circuit measures an electrical property between the electrodes. The leak detector is suitable for a multizone irrigation system that includes a central control unit having a central control system interfaced with a central valve and a central communication unit. The central valve regulates water flow for irrigation from a water source and can lower water pressure in the pipes at its output. The central communication unit is constructed to transmit or receive pressure based communication signals providing irrigation information. Each zone includes a sprinkler control unit having a sprinkler connected to a water pipe for irrigation.