Why is the Hot Water Smelly Like Rotten Eggs?

Why is the Hot Water Smelly Like Rotten Eggs?

Some consumers have submitted comments about unpleasant odors similar to rotten eggs that seemed to come especially from the hot water. The rotten egg odor is caused by hydrogen sulfide (H2S) gas.

The environment in water heater tanks provides an ideal environment for the production of hydrogen sulfide gas,since modern steel water heaters mainly are glass-lined to prevent corrosion.

When a water heater tank is filled with water, an electrolytic reaction begins in areas that have exposed steel. In areas with sulfides in the water, there is a reaction with magnesium anodes which creates hydrogen sulfide gas that produces a rotten egg smell in the water. Smelly water conditions typically occur in private water heater located within the high hardness areas.  

Sediment also is a breeding ground for bacteria thatcan cause the hot water to smell like rotten eggs.