The invention provides a comprehensive energy saving water heater. The comprehensive energy saving water heater comprises an electric heating wire, an ultraviolet lamp, a pressure sensor, a temperature sensor, a TDS detection device, a liquid crystal display screen, a processor, a relay module, an alarming module, a storage module, a power module, a solar cell panel, a photovoltaic controller, a storage battery, an inverter and a double-power-supply switcher. According to the electric water heater, the conditions of the water quality in the water heater can be detected through the TDS detection device, bacteria and the like are removed in time through an ultraviolet sterilization manner when the water quality is poor, and sanitation of the water quality is maintained. In addition, power can be supplied through solar energy, when sunlight is sufficient, charging is conducted automatically or an electric wire is heated through a power supply in a solar storage battery, and energy is saved. In addition, the comprehensive energy saving water heater is simple in structure, convenient to install and use, economical, practical and high in practicability.