The Cause Of Rotten Egg Odor
By far the most common cause of smelly water is bacteria that is in some water and it's this bacteria that reacts with other minerals in your water as well as the aluminum anodes in your water heater that creates the hydrogen sulfide gas, making the rotten egg and sewer odor that you smell in your water.
The problem is most common in well systems, either private or municipal.
Softening using a conventional salt based water softener can make smelly water much worse.
I see customers purchase thousands of dollars worth of water filtering equipment to rid their water of this odor and it would not help most of the time.
The most common odor complaint "Rotten Egg Smell" is derived from Hydrogen Sulfide Gas dissolved in the water. Concentrations as little as 1 ppm, can result in this odor.
Most often "smelly water" will be noticed with well water or when a water heater has not been used for a long time allowing the accumulation of this hydrogen sulfide gas. Active use of the water heater may reduce the problem.
The smell is an effect of four factors that must all be present for the odor to develop. These factors include:
- A high concentration of sulfate in the raw water
- Sulfate reducing bacteria, non-toxic to humans (sulfate is reduced to a sulfide state by the bacteria)
- Little or no dissolved oxygen in the water. Hydrogen (a component of water may be present due to water conditions reacting with the anode).
With these factors the hydrogen and sulfur combine to form the hydrogen sulfide gas that gives off the rotten egg, smelly, odor to the water.
A water heater has at least one anode rod for corrosion protection. Sulfur odor can most easily be eliminated by replacing the anode(s) with one of less active material (Aluminum) and then chlorinating the water heater tank and all hot water lines with a household bleach.
Replacing the Anode Rod can reduce hydrogen ions and eliminate the sulfate reducing bacteria introduced into the water heater through the water supply, therefore "smelly water" can be eliminated.
Chlorination of your water heater may help for a short time or for water heaters where the "smelly water" condition only occurs when the water heater has not been in use for a long time. We also recommend "Flushing" the tank every year to remove calcium sediment in the tanks bottom.
A long-term resolution may require chlorination of your well or water supply into the home.
Depending on your water condition, we also may recommend an Iron/Sulfur Filter System to help cure this issue.
I highly recommend having your Water Tested to make sure there is nothing in your water coming from your well causing this problem. Once your water has been tested, then you can move toward the chlorination process.
Most water treatment professionals will tell you to not remove the anode completely because this will shorten the life of the water heater and possibly void the warranty but if your replacing it with an aluminum anode you should not void your warranty.