The water meter is mainly composed of meter case, impeller metering mechanism, dial indicating mechanism, magnetic control switch and induction magnetic needle. The water flows into the water meter through the water inlet, flows into the impeller box from the lower row hole of the impeller box, pushes the impeller to rotate, and flows out of the water meter from the upper row hole of the impeller box. The rotation of the impeller drives the gear, and the gear drives the digital panel to display the total water consumption through a series of decelerations. Each revolution of the induction magnetic needle, its upper double control switch outputs a signal, representing the flow of a unit of tap water.