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Sulfur Smell in Water – Why it Happens and 6 Fixes

The smell of rotten eggs when you turn on the tap is one of the most unpleasant water problems you can have, and it is usually caused by sulfur compounds.

The sulfur smell can occur in both hot water and cold water and if you have a contaminated water heater, you might smell sulfur more frequently after your water is heated.

So why does your water smell like rotten eggs and where is the sulfur coming from?

Let us learn more about this chemical and its effect on your water supply.

Sulfur smell in water

What is Sulfur?

Sulfur is the fifth most common element on Earth, and it naturally occurs as sulfide and sulfate minerals.

It is considered an essential element in living cells and is the third most abundant mineral in the body (according to WebMD).

Sulfuric acid is the most common sulfur compound used in industrial processes.

In agriculture, it is used to make fertilizer and is a primary component in manufacturing various agrochemicals like fungicides and pesticides.

In addition, sulfur is a primary ingredient in pharmaceutical drugs used for the treatment of various skin conditions, it is used in dye production, and it is used as a bactericide for preserving food and winemaking.

Sulfur stone
Sulfur stone

What is Hydrogen Sulfide Gas?

Hydrogen sulfide gas is a colorless gas that smells like rotten eggs. It has the chemical formula of H2S and is also known as sewer gas, swamp gas, and stink damp.

It is toxic at high levels and is very flammable.

Applications of Hydrogen Sulfide Gas

Hydrogen sulfide gas is used in various fields including:

  • oil and gas refinery
  • mining
  • tanning
  • pulp and paper processing
  • rayon manufacturing

Natural Sources of Hydrogen Sulfide Gas

You can find hydrogen sulfide in these natural sources:

  • sewers
  • manure pits
  • well water
  • oil and gas wells
  • volcanoes

Why Does My Water Smell Like Rotten Eggs?

Rotten egg smell

A sulfur smell or rotten egg smell can sometimes appear in your water supply and there are three main reasons why…

Sulfur Bacteria

One of the primary reasons your water smells like sulfur is the presence of sulfur bacteria.

Similar to coliform bacteria and iron bacteria, this bacterium is a common problem in well water and plumbing systems.

These bacteria decompose organic matter and produce hydrogen sulfide gas.

High phosphate levels in your water can also contribute to bacteria and unpleasant odors.

The bacteria can accumulate in your water heater or water softener tank and affect both hot water and cold water.

Hydrogen Sulfide

The presence of hydrogen sulfide at the water source is a possible direct cause of the water supply’s stinky rotten egg odor.

Hydrogen sulfide gas can contaminate your water in different ways.

One way is that it naturally occurs in soil, rocks, and decaying matter interactions, and then contaminated water flows into the water supplies.

Another way it is produced is by sulfur bacteria in well water or groundwater.

Lastly, it could be due to pollution of surface water or groundwater by a surrounding factory or landfills where hydrogen sulfide gas is produced or leached.

If your cold water smells, then this may be the cause.

Water Heater Problems

If the smell varies depending on the water temperature, then one possible source is from the hot water heater tank in your home.

An anode rod is installed in your water heater tank to reduce corrosion.

Many hot water heater tanks include a magnesium corrosion control rod that can cause a chemical reaction that converts naturally occurring sulfates to hydrogen sulfide.

If your hot water heater shows signs of magnesium rod reactions, you need to replace the anode rod or buy another water heater. An aluminum rod can be used as an alternative to magnesium.

Water heaters need regular maintenance, especially to test the anode rod for corrosion protection and to prevent the release of bad odor smalls from hot water at the point of use.

How to Detect Sulfur in Water?

Sulfur smell from well water

There are several ways to test for the presence of hydrogen sulfide and similar substances in the water.

Here is a list of the methods to test for hydrogen sulfide contamination in the water supply including well water and groundwater.

  • Bacterial Slime – changes color in water mainly in four colors: white, grey, black, and reddish-brown.
  • Black Stains – Silverware, kitchen sinks, washing machines, and plumbing fixtures will have black stains.
  • Constant washing can discolor copper and brass utensils.
  • Corrosion – Metal parts in the plumbing system show signs of corrosion.
  • Sulfur Smell – Water smells like rotten eggs.
  • Water Testing – Water testing kit or testing laboratory results show sulfur content in the water sample. The U.S. Environmental Protection Agency (EPA) recommends private deep wells have the water tested regularly for contaminants. A simple TDS reading would not show a sulfur problem and other tests would be necessary.

Is Water with Sulfur Smell Safe to Drink?

You have to remember that sulfur is an essential nutrient to living organisms including humans and is not considered dangerous at low levels.

The hydrogen sulfide gas dissipates when the water is exposed to the air. Health problems are possible if you run hot water in an enclosed space for a long time and the gas becomes more concentrated.

This means it is still safe to drink hot and cold water with rotten egg odor.

Is it safe to drink sulfur water?

Safe Level of Sulfur

According to the U.S. Environmental Protection Agency (EPA), there is no MCL (Maximum Contaminant Level) for hydrogen sulfide in drinking water.

The standard in drinking water for sulfate (a related compound without any smell) is 250 milligrams per liter (mg/l or ppm).

The odor of water with as little as 0.5 ppm of hydrogen sulfide concentration is noticeable by the majority of humans. Concentrations less than 1 ppm produce a “musty” or “swampy” scent in the water. A 1-2 ppm hydrogen sulfide level gives water a characteristic “rotten egg” odor and may be offensive to inhale.

What are the Benefits of Sulfur in Water?

According to Very Well Health, there are several benefits for your body.

  • helps in the production of antioxidants and amino acids
  • prevents dandruff
  • used for osteoarthritis treatments
  • reduces symptoms of allergies
  • effective in curing rosacea

What are the Risks of Sulfur in Water?

High hydrogen sulfide levels in the water supply have negative effects.

Health Risk

When it comes to your health, you will suffer several symptoms if your body has too much sulfur.

Some of the health effects are:

  • dehydration
  • diarrhea
  • dizziness
  • headache
  • gastrointestinal problems
  • nausea

Other Risks

Aside from damaging your body, you can also observe the following negative effects:

  • pipe slime which can accumulate and clog the pipes in your water plumbing system
  • reduces bleach effect making it ineffective
  • damage to water-using appliances

How to Remove Rotten Egg Smell from Water?

There are several ways to remove the sulfur odor from your tap water including chemical reactions and filter systems.

Hot water smells like rotten eggs


This method involves adding air into your water.

Since oxygen-deficient environments are perfect for sulfate-reducing bacteria to produce hydrogen sulfide, adding oxygen to the water can effectively reduce the level of hydrogen sulfide.

Neutra Sul

This product is also known as hydrogen peroxide.

If your water smells like rotten eggs, adding this product via an injection system can neutralize the sulfur odors through oxidation.

The solution effectively improves the tap water quality both color and taste while minimizing corrosion and scaling in the plumbing system.

Chlorine Bleach

One common water treatment method used by your local water system is continuous chlorination. While effective at reducing microorganisms, public water chlorination is not without its drawbacks.

Chlorine can effectively eliminate odors from the water distribution system so consumers cannot smell any sulfur odor.

Disinfection with a chlorine bleach solution is the recommended treatment for rotten egg smell in water softener tanks according to sources like the Minnesota Dept. of Health.

Iron Removal Filters

There are specific iron removal whole house filters that react with hydrogen sulfide and turn it into inorganic sulfur.

This type of filter is ideal for moderate to high levels of hydrogen sulfide, especially in well water.

A simple carbon filter can help with any type of odor problem in household water and is often included as a filter stage in larger filtration systems.


Potassium permanganate (or Greensand) is an alternative water treatment that can remove odor as well as copper rust and manganese from the water.

During its oxidation, iron, hydrogen sulfide, and manganese are dissolved.

Greensand is a common filtration media in whole house water filters.

Whole House Water Filtration System

Unlike iron removal filters or activated carbon filters, a whole house reverse osmosis water filtration system will remove all kinds of harmful contaminants in large concentrations as well as the odor produced by hydrogen sulfide.

Reverse osmosis will greatly improve the quality of tap water and solve the rotten egg odor problem.

If you prefer chlorine-free water and want to remove other contaminants as well, then this is an option to consider.

Filtered water
Clean filtered water

Next Steps

No one wants to smell rotten eggs when they turn on the tap or step into the shower.

If you smell a sulfur odor when you turn on your tap, don’t worry!

The water is safe to drink and consume but if you have this problem in your home, you can take the following steps:

  • Have a professional plumber check your water heater and plumbing for signs of bacteria
  • Test your source water or talk to your water provider
  • Install a whole house water filtration system that will remove or convert the hydrogen sulfide gas

Once this problem is solved, you will breathe easier every time you use water.