Abstract: A safe water heater comprises a housing assembly, a box assembly, and a water inlet and outlet assembly. The housing assembly comprises a first housing with a mounting cavity. The box assembly comprises a water tank with a water-containing cavity. The water inlet and outlet assembly comprises a water inlet subassembly and a water outlet subassembly. The water inlet subassembly comprises a second water inlet pipe communicating with the water-containing cavity, a first water inlet pipe able to communicate with outside, and a leak-proof mechanism. The leak-proof mechanism is capable of sealing a water inlet of the second water inlet pipe.