If you have a rapid loss of hot water, you may have a problem with the drip tube. This is the pipe attached to the water heater’s cold water inlet pipe that is supposed to heat the cold water by moving it through the hot water to the bottom of the tank where the burner is located. The drip tube is supposed to direct the cold water toward the bottom of the tank so that it does not go over the hot water outlet and out to your faucets. It is possible for the drip tube to fall off inside your water heater. This allows the cold water to rise to the top of your tank, which means that you get cold water within just a few minutes. Fixing the problem requires pulling the cold water inlet pipe to verify that the drip tube is still attached and in good condition.