Smell

• You probably don't spend much time hanging around your hot water heater. The usual way to notice a problem with it smelling is to notice an odor in the hot water coming from your home's faucets. The odor is much like sulfur or rotten eggs. The hot water will be clear, but the bad smell will affect its taste and can make you reluctant to shower in it or use it to wash laundry.
  
  

Cause

• The cause of the problem smell in your hot water heater is bacteria living inside the unit. Attracted to the ions produced by the magnesium rod found inside many hot water heater tanks, they excrete hydro-sulfide gas. The gas dissolves in the water in the tank, imparting the distinctive odor of sulfur. While unpleasant to smell and drink, the bacteria are not a health hazard to you or your family.
  
  

Solution

• To get rid of the smell, get rid of the bacteria inside the tank. You can kill them by raising the temperature of the unit over 140 degrees Fahrenheit. Leave it at the elevated temperature for several hours; be sure to warn everyone in your household about the change so they do not scald themselves with hotter-than-expected water. The heat will kill the bacteria. After five or six hours, drain all water from the tank, flushing out the tainted water and the dead bacteria. Return the unit's temperature to its normal setting.
  
  

Considerations

• Once sulfur bacteria show up in a hot water heater, they often return. If they do, get rid of them and the bad smell by raising the temperature of the unit, then flushing the tank. If you keep your hot water heater set below 140 degrees Fahrenheit to save energy, you are at increased risk for bacterial growth inside the tank. Removing the magnesium rod from the tank can make the hot water heater less attractive to bacteria, but it might void the unit's warranty.