A common sign of a broken water heater is spotting a pool of water on the floor near the tank. Leaking can occur in tanks that are more than six years old. There are several other telltale signs that a water heater needs repair or replacement.
Broken water heaters often have worn-out valves, making it impossible for the tank to produce hot water at normal temperatures. When it's necessary to manually adjust the temperature higher, the heater has corrosion issues. Sometimes hot water stops flowing from the tank altogether, which may be due to a malfunctioning heating element. Water may also stop flowing due to an accumulation of sediment building up in the bottom of the tank. As the sediment sits there over time, it deteriorates to the point of causing irreparable damage.
Any type of unusual noise coming from the water heater is a sign of trouble. Typical noises of a broken water heater include creaking, whining or knocking. Noises are usually the result of sediment buildup inside the tank. In some instances, the pilot light doesn't stay lit in a gas water heater, which is commonly caused by a broken safety limit switch. Rust is a major problem for water heaters and can wear down important elements of the heater.