Why Does My Well Water Smell Like Sulfur or Rotten Eggs?
Being greeted by the unpleasant smell of rotten eggs or sulfur from your tap is disconcerting to say the least. Homeowners with a private well or small water supplies often suffer from sulfur or rotten egg smells, but it’s usually much more than an inconvenience.
The rotten-egg smell indicates that hydrogen sulfide (H2S) is present and the smell can destroy your shower experience and cause you to wonder about the safety of your drinking water; however, it is very treatable.
I am going to help you explain the reasons for the rotten egg smell in water, how it may be in your well, and how to permanently eliminate the rotten-egg smell from your water.
How Did the Rotten Egg Smell Get in Your Water?
Most of the time, the rotten egg smell in your water is caused by hydrogen sulfide (H2S) gas that is dissolved in your well water.
While the concentration of H2S at these lower levels does not pose a health risk, it is very corrosive and usually indicates a greater water quality problem.
In general, there are three common ways H2S enters your water supply.
1. Sulfur Bacteria in the Well
Most commonly the source of H2S in a well is due to sulfur-reducing bacteria. Sulfur-reducing bacteria feed off of organic matter and consume sulfur instead of oxygen as their method of energy production.
Sulfur-reducing bacteria, in their absence of oxygen, create hydrogen sulfide gas.
2. Chemical Reaction with Water Heater
Sometimes the rotten egg smell is limited to just hot water. In this case, when the magnesium anode rod in the water heater creates chemical reactions with sulfates in your water, H2S gas is created.
3. Sulfates in Groundwater
Some groundwater has naturally dissolved sulfate in it, and where this water exists in such areas as shale and sandstone formations that have low oxygen levels exist.
Identifying the Source
When determining how the rotten egg smells entered your home, it’s helpful to note when the odor occurs. If the smell is in both the hot and cold water, it is likely from your well or main water line.
If the smell is just in the hot water, then it is likely the water heater.
Lastly, any concentration of H2S that produces an odor is considered an aesthetic (smell/taste) problem more than a direct health hazard. However, it is vital to test your water with a qualified, local water technician, as the presence of H2S can mask and accompany more serious water quality problems.