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Hot Water Heater Smells Like Rotten Eggs? 4 Easy Fixes!

Scott Winfield
Written by Scott Winfield
Last Updated on

Dealing with the unpleasant smell of rotten eggs in your hot water?

Many homeowners face this issue, which is often caused by hydrogen in the water heater. This can be frustrating and concerning, especially regarding the safety and quality of your water.

To help you get rid of this annoying issue, we’ll walk you through four simple and effective fixes so you can ensure your water is fresh and clean.

Here’s a quick overview of different ways hydrogen sulfide can manifest in your water heater:

Hot Water Heater Smells Like Rotten Eggs? 4 Easy Fixes!
Hydrogen Sulfide SourceSolution
Leftover warm water in your water heaterFrequently discharge leftover hot water from the tank Always make sure the tank is empty
Sulfur-reducing bacteria (SRB) in your water heater tankApply a concentrated chlorine treatment to your tank Flush the tank or completely replace your water heater
Contaminated water source (mostly well water)Get a Sulfur Water Filter (Our recommendation: Springwell Sulfur Filter)   Get a chemical injection system (Our recommendation: Springwell Injection System)   Get a Hydrogen Peroxide System: (Our Recommendation: US Matrixx System)
Magnesium Anode rods reacting with sulfides in waterReplace magnesium rod with aluminum or zinc rod
Sulfur-reducing bacteria (SRB) in your water softener tankClean/Flush your water softener tank Consider installing a water filter

Why Does My Hot Water Smell Like Sulfur?

If you notice your hot water smells like rotten eggs, hydrogen sulfide is likely to blame. This gas can leak from your faucets and fixtures, causing that awful sulfur odor. It might also cause greasy black or yellow stains on your sinks and appliances.

Hydrogen sulfide can come from various sources. It could be your water heater’s tank or somewhere else in your plumbing system, like the building’s pipes or the city’s water supply.

Although the gas in your pipes isn’t usually harmful, since its amount is probably negligible, it can cause minor health issues such as eye irritation, dizziness, and digestive upsets.

The good news is that our noses are very sensitive to even small amounts of hydrogen sulfide. If the water has dangerously high levels of the gas, it’d be so pungent that you wouldn’t even consider drinking it or bathing with it.

Here’s a closer look at what might be causing the problem and some tips to help you get rid of the smell.

1. There’s Leftover Warm Water in Your Water Heater Tank

Warm Water Left in Tank
Warm Water Left in Tank

Your water heater’s tank is a common place to start when tracking down that rotten eggs smell. If there’s leftover warm water sitting in your heater’s tank, it can become a breeding ground for bacteria. In this case, simply emptying the leftover warm water might completely eliminate the smell.

Some of those bacteria are also known as sulfur-reducing bacteria (SRB). They thrive on small amounts of sulfur present in the tank. The more they feed off the sulfur, the more they reduce the ratio of elemental sulfur to hydrogen sulfide gas. This, in turn, causes the rotten egg smell.

The Solution:

The solution to removing rotten eggs smell caused by sulfur-reducing bacteria (SRB) in your water heater tank is relatively straightforward: Apply a concentrated chlorine treatment to your tank. Simply add chlorine to the tank and let it circulate through the pipes and tank.

Always be mindful when you are using chlorine. After applying it, you won’t be able to use the water heater for at least 24 hours, as chlorine needs to completely evaporate from the water before it’s safe for use.

The chlorine treatment approach should be enough to eliminate the smell. However, in some cases, this solution might not work.

Another thing you can try is to flush the tank, which can permanently eliminate the bad smell. Naturally, you’ll need to completely dismount the heater, so you’d want all the help you can get. If you hire a qualified plumber, you can also ask them to clean the inside of the tank in order to remove the smell entirely.

If all else fails, replacing the water heater might be necessary. If you do end up replacing the water heater and the smell still persists, the problem likely lies elsewhere in your water system.

2. Your Water Source is Contaminated

Your Water Source

If you rely on a private well for your water supply, you might be dealing with contamination. About 13% of the U.S. population, or 43 million people, use private wells for their water supply and sometimes report a smell of rotten eggs. This could happen when groundwater wells get infested with sulfur-reducing bacteria (SRB).

An infestation usually occurs due to low oxygen levels and warm temperatures. To check if your well is the culprit, run cold water through your faucets for a while. If the smell persists, it confirms that the problem is with your well, not the water heater.

The Solution:

Unfortunately, there are no quick fixes when it comes to contaminated wells. But, you can start by trying some well-cleansing tablets or solutions, like the NuWell-100 Pelletized Well Cleaner. This might not completely eliminate the problem, but it’s worth a try before investing in a more expensive water treatment system.

Here are some other treatment solutions for contaminated wells:

  • Chlorination Systems: These systems work by injecting a small amount of chlorine into the water supply to effectively kill bacteria. However, you’ll have to purchase a de-chlorinating carbon filter to remove the chlorine smell and remnants after the water has been disinfected. This is the only way of making your water safe for human consumption after chlorination.
  • Hydrogen Peroxide Filters: These filters are another effective method of removing sulfur. They’re also known to dilute and remove iron and manganese minerals. Upon installation, the hydrogen peroxide pump will continuously add 25 parts per million (ppm) of H₂O₂ to the water to remove the sulfur. Combining the hydrogen peroxide-treated water with a carbon filter or water softener can effectively eliminate sulfur and other well-water contaminants.
  • Backwashing Filters: These filters are another common way to remove hydrogen sulfide from water. They come in large tanks and convert insoluble sulfur to soluble sulfur. They are able to clean and renew themselves by backwashing. During the backwashing process, they reverse the water flow so that it enters from the bottom of the filter bed. That said, your water needs to be at a pH level of at least 8 for these filters to work effectively.
  • Aeration Systems: Aeration is another effective way to get rid of unpleasant odors coming from your well because it can reduce the total amount of hydrogen sulfide in the water. If you opt for this approach, make sure to consult with a professional plumber to assist you in choosing a system that will work best in your circumstances.

Keep in mind that you may need to completely replace your water heater even after installing a new water treatment system if the rotten egg smell continues to linger.

3. Magnesium Anode Rods Reacting With Sulfides in Water

Magnesium Anode Rods
Magnesium Anode Rods

Many gas and electric water heaters use anode rods to prevent tank corrosion. These rods, often made of magnesium, zinc, or aluminum, absorb corrosion and protect the walls of the heater tank. However, in some cases, they can cause a reaction with sulfates in the water, creating hydrogen sulfide gas and causing that rotten egg smell.

Magnesium anode rods are generally beneficial because they provide excellent corrosion protection and add small amounts of magnesium to your water supply, which can be good for your health. Unfortunately, magnesium anode rods can also cause this unpleasant reaction with sulfates, resulting in excess hydrogen sulfide.

The Solution:

An easy fix is to replace the magnesium anode rod with an aluminum or zinc rod. This should help eliminate the unpleasant smell. Aluminum and zinc rods are less prone to causing the reaction that produces hydrogen sulfide gas.

Aluminum and zinc rods are also less expensive and last longer than magnesium rods. However, they can cause sediment buildup, leading to cloudy tap water. Aluminum zinc rods are a non-toxic option and don’t react with the sulfates in your water, but they too might need to be replaced more frequently.

By swapping out the anode rod, you should notice a significant reduction in the sulfur smell from your water heater.

4. Sulphate Reducing Bacteria in Water Softeners

Install a Home Water Softener
Water Softener

If you have a water softener installed, it could be the source of the rotten egg smell. Water softener tanks are prime environments for sulfate-reducing bacteria (SRB) because these bacteria thrive on the sodium found in water softener tanks.

The Solution:

Start by calling a professional to clean your water softener tank. If your tank is still under warranty, take advantage of that and schedule a tank cleaning. It’s a good idea to clean the water softener tank at least once a year to prevent SRB buildup.

You can also install a water filter alongside your water-softening system. The filter will help remove sulfur and iron, reducing the SRB buildup in the water softener tank. Consulting with a professional for the filter installation is recommended. They can test your water supply and determine the best filter for your needs.

Regular maintenance and the right filtration system should help keep your water softener free of bacteria, ensuring your water stays fresh and odor-free.


If your hot water smells like rotten eggs, don’t worry – there are effective solutions.

Whether it’s leftover water in the tank, contaminated well water, reacting anode rods, or bacteria in your water system, each problem has a fix. Often, these issues can be resolved with simple steps like cleaning, replacing components, or adding treatment systems.

If the smell persists, consulting a professional can save you time and ensure your water is fresh and safe. Addressing these issues promptly will help you keep your home’s water pleasant and worry-free.

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Scott Winfield
Scott Winfield
My name is Scott Winfield and researching and writing about water filters and other strategies to purify water has become my full time passion in recent years. I'm glad that you found our site and you can look forward to authoritative and well researched content here to help you get the best in water.
  1. I never had this problem with my well water until I turned my water tank temperature from 140 degrees down to 120. I like the lower temperature but the higher temp kills the bacteria. All the business you hear on other sites about replacing your water heater is salami.

  2. The article offers practical solutions to address this problem, such as flushing the water heater, disinfecting the system, or consulting a professional plumber if needed. It’s also helpful that the article emphasizes the importance of regular maintenance and testing water quality to ensure safe and odor-free hot water. Overall, this article provides clear explanations and actionable steps to help readers tackle the issue of a rotten eggs smell in their hot water heaters. Thank you for sharing this informative piece!

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