A lack of hot water can be caused by a variety of issues. In electric water heaters, a power loss or heating element failure can cause water to no longer heat in the tank. In gas water heaters, a faulty gas connection, a bad pilot light, or a bad burner can cause no water to heat.

Some of the most common causes of hot water issues include gas leaks, water tank leaks, gas valve failures, pilot light problems, electric heater malfunctions, thermostat issues, faulty heating elements, an undersized tank, and even the weather conditions.