Water Sulfur Smell

Why Does My Water Have a Sulfur Smell?

Every once in a while, you may turn on your tap and notice that your water has a strange, off-putting sulfur smell.  This is one of the most common odors that water can have.  If you don’t know what sulfur smells like, it is usually described as similar to the smell of rotten eggs.

Water Sulfur Smell

The reason your water sometimes smells like sulfur is due to a concentration of hydrogen sulfide gas (H2S). Sulfur is one of over 300 chemicals that are commonly found in drinking water.  Sulfates are found in minerals, soil, and rocks and can easily leach in water sources.

Is Sulfur Harmful?

Sulfate and hydrogen sulfide are the two types of sulfur that are can be found in tap water. While the presence of sulfur in your water will give it a foul odor and can sometimes affect the taste, it is safe to drink.  Sulfur and sulfur compounds are not considered harmful at low levels.  At the levels where they would be harmful, the taste and smell would be so unpleasant that most people would find it unpalatable.

Water containing sulfur is considered a nuisance.  It is on the EPA’s list of secondary standards.  This means that it affects the water’s color, taste, odor, corrosivity, and staining, but not its safety.  Although low levels of sulfur do not pose a health risk, they can cause water to become corrosive. Fixtures can become tarnished and stained by the sulfur.


Sulfur Levels

0.5 parts per millionThe minimum amount of hydrogen sulfide concentration that is detectable by humans
1 part per millionSulfur concentrations at this level have a musty or swampy odor
1-2 parts per millionSulfur concentrations at this level have a rotten egg smell and will cause the water to become corrosive
250 parts per millionThis is the recommended maximum level for sulfates from the EPA secondary standards


Sulfates have a bitter taste, but they do not produce any odor.  They are a combination of sulfur and oxygen that is naturally found in the soil.  They can also come from industrial waste, landfills, and old septic systems.  As the minerals dissolve over time, they are absorbed into water sources.

High levels of sulfates in your water can make cleaning difficult as the water is prone to leaving behind stains. This can make it a challenge to clean clothes as well as sinks, showers, and tubs.  It can also attract certain bacteria which can cause the formation of a slimy film inside your toilet tank and bowl.  Sulfates do not cause health issues, but they can have a laxative effect.

Hydrogen Sulfide

The presence of hydrogen sulfide in your water is easily noticeable because of the strong sulfur or rotten egg smell.  The smell may only be present when the water is first turned on.  It may be more noticeable when using the hot water.

Hydrogen sulfide is a gas that forms as organic matter is being decomposed by bacteria.  These bacteria thrive in landfills, wells, and water processing equipment like water softeners and water heaters.

Water that has a high concentration of hydrogen sulfide can be corrosive.  It may damage pipes and plumbing fixtures over time.  Similar to sulfates, it generally does not cause any serious health issues.  At higher levels, it can cause nausea.

Getting Rid of the Sulfur Smell

There are a number of treatments available if you are concerned about the sulfur smell coming from your water.

  • Chlorination can be used to bind to sulfur, leaving behind yellow particles that can be trapped with a filter
  • Aeration causes the sulfur to dissolve
  • Activated Carbon Filters work to absorb sulfur molecules
  • Distillation and Reverse Osmosis are common treatments for small quantities of water
  • Ion Exchange is the typical treatment for large quantities of water

Make Sure Your Water Is Safe

A change in the smell or taste of your water could simply be the result of an increased level of sulfur.  It could also be an indication that something else in your water has changed. TestAssured makes a number of testing kits that you can use to quickly and easily test your water.  With just a few water samples, you can test your water for bacteria and other common contaminants. Any time you notice a change in your water, the best way to make sure it is safe to drink is to test it.

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