The utility model discloses a water heater, include: the inner bag, the inner bag has the drain, the blow off pipe, sewage pipe connection includes in drain, blow off pipe: drain valve pipeline section, drain valve pipeline section have the play water route with the drain intercommunication, and the drain valve pipeline section is built -in to be equipped with the drain valve, and the perisporiumof drain valve pipeline section is formed with the spout, and the drain valve includes: decide the ceramic chip and move the ceramic chip, the periphery wall that moves the ceramic chip is equipped with first connecting portion, move the ceramic chip with the thickness of deciding the ceramic chip all is greater than 3MM, is less than 9MM, knob, knob be rotationally around locating the outer peripheral face of drain valve pipeline section and relative with the spout, the inner peripheral surface of knob be equipped with with first connecting portion complex second connecting portion, the knobmoves the ceramic chip and rotates between the primary importance and the second place, a valve cove. According to the utility model discloses a water heater, through will move the ceramic chip with the thickness of deciding the ceramic chip is set to and is greater than 3MM, is less than 9MM, has effectively reduced and has moved the ceramic chip and decide the phenomenon of rupture of ceramic chip, and then improved water heater's whole quality.