Smell

• If your water-softener tank smells bad, you'll notice the reek of rotten eggs around the unit, especially when you open it. The smell will get into the water in your home that is treated by the unit, causing the water in your kitchen and bathroom to smell of sulfur. There won't be any visible discoloration to your water, but it will be unpleasant to drink and to use in your shower. If you use treated water in your laundry room, your clothes could also begin to smell bad.
  
  

Cause

• Your water-softener tank smells bad because the unit is infested with sulfur bacteria. Found naturally in some rural water supplies, these bacteria also appear in hot water heater tanks and water softeners. They are attracted to water softeners because the units contain sodium. They release hydrogen sulfide gas as a waste product when they feed. This gas dissolves in the water in the unit's tank, giving it the odor of rotten eggs.
  
  

Solutions

• Killing the sulfur bacteria will stop them from producing more hydrogen sulfide. They can be killed with heat or shock chlorination. Drain all water from the water softener tank, and clean the interior. Fill it with new water, then use chlorine to shock the tank. Drain the tank again and clean it -- this removes both dead bacteria and chlorine. Fill it again with new water. If the problem is in your hot water tank, too, use heat to kill the bacteria by raising the temperature to over 140 degrees Fahrenheit for a few hours. Drain the water heater's tank to flush the dead bacteria out, and return the unit's temperature to normal.
  
  

Considerations

• Before taking steps to get rid of the smell in your water-softener tank, read the manufacturer's guide. There's a chance that performing shock chlorination on your own could void the unit's warranty. If this is the case, contact a professional to do the job. When emptying and cleaning the unit's water tank for the first time, look for black slime at the bottom. Sometimes the bacteria will produce so much hydrogen sulfide that particulates coat the interior of the tank.