it's the water; here's why.
Posted by jimbo on April 29, 2004 at 09:20:13:
In response to it's the water; here's why.
: Understand that this problem is caused by your WATER, NOT the water heater. The rotten egg odor is the result of iron bacteria and sulfate reducing bacteria acting on the dissolved hydrogen sulfide gas in the water. The bacteria come from the water source, and multiply inside the tank. The gas also is in the water from the source. The cathodic action of the magnesium anode rod provides a source of excess hydrogen ions to facilitate the reaction.

Once again, the problem is (a) in the water and (b) in the bacteria growing in your tank. See this excellent weebsite for an explanation of the problem and how to deal with it: