Smelly Water Problem

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:

1. A high concentration of sulfate in the raw water
2. Sulfate reducing bacteria, non-toxic to humans (sulfate is reduced to a sulfide state by the bacteria)
3. Little or no dissolved oxygen in the water
4. 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. Smelly water can most easily be eliminated or reduced by replacing the anode(s) with one of less active material and then chlorinating the water heater tank and all hot water lines with a household bleach.

Replacing the Anode Replacement can reduce hydrogen ions, but does not eliminate the sulfate reducing bacteria introduced into the water heater through the water supply, therefore "smelly water" can still be present. 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. A long-term resolution may require chlorination of your well or water supply into the home.

Chlorination Procedure