Strange noises occur when steam builds up beneath the scale. If water sounds like it is boiling inside the tank, it could indicate overheating and a dangerous pressure buildup.

To minimize corrosive minerals through ionization, water heaters have a magnesium or aluminum anode rod, inserted through the top of the tank. To avoid scale in the first place, open the drain valve at the base of the tank and flush about a gallon of water through every few months.

Follow the manufacturer's recommendations. Be sure to hook up a hose or allow for proper drainage of the scalding hot water before opening the valve.

Electric water heaters may also get a buildup of scale on their heating elements that causes similar sounds. Have the elements replaced.

Note: Always shut off the power to an electric water heater before working on it. Do not work on an electric water heater if there is standing water pooled on the floor near the appliance. Shut off the circuit to the water heater, and call a repairperson.