Why does my water smell like rotten eggs and how did it get there?
If you notice this smell in your drinking water, it probably contains hydrogen sulfide (H2S) gas.
Hydrogen sulfide gas produces a strong and unpleasant “rotten egg” or “sulfur” odor and taste. In some cases, the odor may be present only when the water is first turned on or when hot water is run. Heat forces the gas into the air which may cause the odor to be especially offensive in a shower.
Sources of this gas include:
- Decay of organic matter or chemical reactions with sulfur-containing minerals in soil and rock.
- Sulfate-reducing bacteria which convert naturally occurring sulfate and other sulfur compounds to hydrogen sulfide gas.
- Water heaters can produce hydrogen sulfide gas by:
- Providing a warm environment for sulfate-reducing bacteria to live.
- The magnesium anode supplies electrons that sustain the reaction of sulfate to hydrogen sulfide gas.
Is sulfur harmful?
Sulfur, sulfates and hydrogen sulfates are not generally considered harmful because the taste and odor is so unpleasant at such low levels that the taste and smell would prohibit most people from drinking it well before it reached harmful levels.
It is mainly considered a nuisance primarily because of the smell and taste, but also because it can be corrosive to metals such as iron, steel, copper and brass. It tarnishes silver and can discolors copper and brass utensils. Hydrogen sulfide can cause yellow or black stains on kitchen and bathroom fixtures. Coffee or tea may be discolored and the appearance and taste of cooked foods can be tainted at times.
Ways to get sulfur and the smell of rotten eggs out of drinking water.
Chlorine will quickly react with hydrogen sulfide to form a tasteless, odorless, yellow particle. A small amount of chlorine, even household laundry bleach, can be added to any water system to remove hydrogen sulfide. The yellow sulfur particles that remain form a yellow film on clothing and fixtures. A sand or aggregate filter can remove the yellow particles.
Oxygen in the air will react with hydrogen sulfide to form an odorless, dissolved form of sulfur called sulfate. Some yellow sulfur particles may also form after the water is aerated. In an aeration system, compressed air can be injected into the water system but must then be removed from the water.
Very small amounts of hydrogen sulfide can be removed from water with activated carbon filters. The hydrogen sulfide is adsorbed onto the surface of the carbon particles. Periodically, the activated carbon filter must be replaced depending on the amount of hydrogen sulfide in the water. Moderate to high levels of hydrogen sulfide in water will require very frequent filter replacement.