If you have hard water, the minerals in that water can cause problems for your water heater. Scale, mostly calcium and magnesium, is a buildup of minerals inside the tank. This buildup can greatly reduce the life of the unit and cause it to operate longer than necessary. The electric bill increases as a result. Preventing scale buildup can keep your heater operating well for many years. An annual tank flushing is suggested to remove accumulated mineral deposits. Check your owner’s manual for information.