The anode attracts elements that cause rust, and in doing so rusts away itself and should be replaced about every five years. If the anode is causing a strange odor in the water, have the water analyzed to see if water-conditioning equipment needs to be installed in place of the anode. A water heater's relief valve is an important safety device. If the home's hot water is too hot or the pressure seems to be unusually high, check the relief valve. If water is dripping from the valve, it may need to be replaced.
Proper ventilation is also important for a water heater.
If soot accumulates on top of a water heater, call a professional. The burner may be malfunctioning. One way to check for proper ventilation is to hold a flame near the draft hood. If the ventilation pulls the flame in toward the hood, then the water heater has proper ventilation. Buy a battery-powered water sensor to guard against leaks.