Dealing with Water that Smells Like Rotten Eggs

Guide to identifying and solving sulfur water problems causing a rotten egg smell


Is there anything more distasteful than water that smells like rotten eggs? And when it comes from your water, the permeating smell of rotten eggs lingers throughout your house.

This rotten egg smell is present in various sources of groundwater. Since it’s coming from the ground, it is highly dependent on groundwater and aquifer conditions. Because of this water that smells like rotten eggs usually affects many wells in a local area. In upstate New York, while water that smells like rotten eggs is less common near Lake Ontario, near the Finger Lakes it is much more common.

In the past, when people used mostly shallow wells or surface water like rivers and lakes for their primary water sources, the sulfur smell in water was rarely an issue. To supply today’s water-hungry population, more deep wells are being drilled. Since the egg smell in well water originates primarily from deep well sources, this problem is more of an issue than ever.

Understanding the Rotten Egg Smell

What causes water to smell like rotten eggs? The rotten egg smell in water has the technical name of hydrogen sulfide, also called sulfur. Since hydrogen sulfide is the most common reason that water smells like rotten eggs, the term “sulfur” has become almost synonymous with any unpleasant smell, whether or not it is actually caused by hydrogen sulfide. However, in this article, we’ll be focusing mainly on the sulfur that causes water that smells like rotten eggs.
The rotten egg water smell is a dissolved gas and is formed in groundwater sources when sulfur-reducing bacteria feed on small amounts of sulfur, found either in the water or in the ground. These bacteria thrive in low-oxygen habitats like aquifers, wells, or your home’s plumbing.
In some cases, only the hot water may have a sulfur smell. This is usually related to water reacting with the anode rod of the water heater. Since this is different in a way compared to sulfur water from wells, we may examine this in greater detail in a later article. 

Effects of Sulfur Water

  1. Health Effects: Sulfur is an essential element, and slight levels do not pose a health risk for the most part. Is it safe to drink water that smells like sulfur? This depends on the levels of sulfur in your water. High levels of sulfur in water can lead to diarrhea and dehydration. Infants are the most susceptible to these side effects (see this article from the state of Oregon’s website).
  2. Environmental Effects: The aesthetic effects of sulfur are what give it the most reason for disagreeability. Sulfur gives water an awful taste and smell. Hot water only amplifies the smell, since the gas escapes faster from hot water. (Believe it or not, some folks become accustomed to it and live with it). This can leave a rotten egg smell in washing machines, sinks, and clothes.
  3. Household Effects: Senses aren’t the only things that suffer from this rotten egg substance. Sulfur leaves behind a black residue, which causes unsightly staining. The hydrogen sulfide gas is also corrosive. Anything metallic that comes in contact with sulfur, such as plumbing, appliances, and fixtures, and is not corrosion resistant, can have its useful lifespan significantly reduced.

How to Get Rid of Sulfur Smell in Water

1. Perform a Sulfur Water Test

Since the amount of sulfur in the water is a huge factor in determining the most effective treatment method, an accurate sulfur water test is a crucial starting point. One thing that complicates the issue, is that since sulfur is a gas and quickly dissipates into the air, it’s difficult to do an accurate lab test. By the time a sample of water is transported to the lab, the test may no longer be accurate. For this reason, the preferred method to test for sulfur in your well water is onsite, immediately after sampling water from the well.

Another factor that makes testing complicated is that the sulfur content in well water may vary throughout the year. For example, some wells will have low levels during winter and spring. However, during the drought of summer when the water table is low, the level of sulfur can soar. If your sulfur level varies by season, it’s best to perform the test at a time when levels are high. Alternatively, take the seasonal sulfur levels when planning to treat for sulfur to compensate for higher levels.

There are many DIY sulfur water test strips available online. While they likely vary in accuracy an educated idea is better than none. A reputable test both accurate and easy to use but slightly more expensive is Hach’s Model HS-C test kit. It’s only accurate up to 5 ppm, but can be manipulated by diluting the sample with bottled water.

2. Treat the Rotten Egg Smell

Treatment Options

  • Chlorination: Chlorine is a powerful oxidant and its oxidation properties make it quite effective at removing sulfur smell from water when combined with a filtration method of some sort. As a bonus, chlorine treatment also acts as a disinfectant for bacteria control. The disadvantage of chlorine treatments is that they can require a large amount of product to correctly oxidize sulfur, especially in high levels. Also, chlorination can bring its own set of worries because it can create carcinogenic disinfection by-products from reacting with organics in water.
  • Hydrogen peroxide: Like chlorine, peroxide is a powerful oxidant, and is usually even more effective at reducing and removing sulfur smells in water. It is also less expensive when compared to chlorine and less of a concern for creating as many disinfection by-products. On the downside, it is not as effective at bacteria control as chlorine.
  • Aeration: One method that is used sometimes, especially in extreme conditions of sulfur, is to aerate the water. Typically, this is done by spraying the water slowly into a vented atmospheric tank. Aeration gives hydrogen sulfide gas time to dissipate, and from there is pumped on-demand to point of use. This method has the advantage of using fewer chemicals, if any, which makes it less expensive to maintain. However, upfront costs are very high. A large tank, a power vent, a repressurizing system, and more components are usually required. Also, such a complicated design requires lots of space.

Filter Options

  • Oxidation Filters: Some specialty backwashing carbon and sand filters have been designed to capture an air bubble inside a pressurized tank where the water flows. This acts as a small aeration system, yet it only uses a small tank, no chemicals, and no repressurizing pump. It is very effective especially for low to medium levels of sulfur in well water. However, as sulfur levels increase, these systems require more frequent backwashes. The backwashes waste more water, and in extreme levels may not be sufficiently effective.
  • Activated Carbon Filters: Basic carbon cartridge filtration can be a good option for removing very low levels of sulfur. This requires no chemical injection which is a plus. The only maintenance required is to change the filter as needed when it no longer removes all the sulfur. This method of water filtration is very effective for low sulfur levels and low water usage levels. However, when large amounts of water need to be treated, or hydrogen sulfide is high, filters require very frequent replacement. These replacements can get expensive fast.

Other Options

  • Other Treatment Options and Suggestions: In some cases, sometimes an intermittent rotten egg smell from well water, whether hydrogen sulfide or otherwise, can be caused by bacterial growth that can be addressed by shocking the well with chlorine. If this chlorination process sufficiently halts the proliferation of the bacteria, it may not need another shock treatment for months or even years. However, in cases where sulfur is a constant issue, shocking the well usually lasts for only a week or two at the most, and then the rotten egg smell becomes present again. In this case, a constant sulfur treatment method is usually needed. In all cases before shocking a well, consult with a well driller or other professional for specific, directions, tips, or regulations concerning treating a well with chlorine.     

3. Consult Your Water System Professional 

Since sulfur treatment is a technical application, especially when dealing with high levels, it is often best to consult with a water conditioning or water treatment specialist to determine the best methods for your specific scenario. Sometimes they may recommend a combination of two methods, such as peroxide injection with a backwashing filter.


Hopefully, this article gave you hope. Yes, you can live without the negative effects of this rotten egg smell in your water! Again, realize the importance that treating the sulfur promptly is necessary, to keep plumbing and fixtures from corroding and discoloration.

If you are interested in a free water test and consultation to address sulfur or other contaminants in your water, please reach out to us at Aquanology. Our goal is to serve your water conditioning needs at a fair price, coupled with reliable service and advice that you can count on. Reach out to us today to learn more.

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