Why Your Well Water Smells And Tastes Like Sulfur – And How To Fix It

More than one quarter of all Americans who use well water are actually drinking contaminated water every day. An unpleasant sulfur smell from your water could be an indication that you are consuming contaminated water.

Hydrogen sulfide gas is the main cause of well water smelling like sulfur or ‘rotten eggs’. Sulfur-reducing bacteria or industrial activities are typically responsible for the production of hydrogen sulfide gas. Chemical reactions between anodes and sulfates in water heaters, and environmental pollution (in rare cases) can also produce hydrogen sulfide gas.

This article will explain the causes of sulfur smell in well water, how to identify hydrogen sulfide contamination, and more importantly, how to treat well water to remove the smell.

3 reasons why well water smells like sulfur (rotten egg)

1. Sulfur-reducing Bacteria

Sulfur-reducing bacteria have high survival and growth rates in low oxygen environments, like groundwater wells and plumbing systems. These organisms feed on small amounts of sulfur and produce hydrogen sulfide gas as a by-product, giving the water a strong sulfur smell.

In contrast, sulfur-oxidizing bacteria convert sulfide into sulfur and can leave a slime deposit on pipes and screens. However, they do not create a sulfur smell. 

If your well water smells like sulfur, it is most likely the result of sulfur-reducing bacteria.

Sulfur-reducing bacteria feed on organic matter, in addition to human and animal wastes. They are common in the environment – but not welcome in your well water!

2. Industrial activities

Hydrogen sulfide naturally occurs in petroleum and natural gas. 

Industrial activities, such as petroleum/natural gas drilling and refining, wastewater treatment or paper milling can often cause the release of hydrogen sulfide gas. If you are located near some of these industries, this may be the cause of your sulfur smell

Hydrogen sulfide gas can also be produced naturally at hot springs, such as the hot springs at Yellowstone, or Glenwood in Colorado. Because of this, hydrogen sulfide gas can naturally occur in your groundwater, and give your well water a rotten-egg smell.

3. Water heaters

Hydrogen sulfide gas can accumulate inside your water heater because of a chemical reaction.

Water heaters usually contain a sacrificial ‘anode’ – a metal rod, whose sole purpose is to corrode instead of your water heater (hence the term ‘sacrificial’). The anode can react with sulfates that are in your water to produce hydrogen sulfide gas.

Sulfur-reducing bacteria may also be present in water heaters. Although, this is because they provide a nice, warm environment for them to thrive in, especially if you haven’t used the water in your water heater in a while.

If you notice the sulfur odor coming from your hot water, then the water heater is most likely the source of the hydrogen sulfide and the anode will need replacing.

How To Detect Sulfur In Water

The smell or taste of sulfur (or rotten-eggs) from your water, and the discoloration of home appliances are the easiest ways to detect the presence of sulfur in your well water. However, periodic water testing for hydrogen sulfide is more confirmatory and informative as to your course of action.

Well water testing kits are readily available online, affordable, easy to use and provide results within minutes.

We recommend this well water testing kit that specifically tests for hydrogen sulfide, available from Tap Score.

Tap Score has several options available for well water testing; however you only need the basic level “Essential Well Water Test” to test for hydrogen sulfide. They also provide detailed on how to conduct the test and understand your results.

For this purpose, it is advisable to test water from all the different water supplies coming from your well, and especially, the hot and cold water. This is important to determine the source of the hydrogen sulfide odor and will determine which treatment method you should use.

The test kits come with a strip and step-by-step instructions for use. Follow the instructions and leave the strip in the different water samples to stand until there’s a noticeable change in color.

If the change only occurs only in the hot water sample, then you should check your water heater as this is most likely the problem. If there’s a color change in both, then your treatment should focus on the well itself.

At this stage, paying a laboratory for water testing may be necessary to give you a better idea of how much hydrogen sulfide contamination you’re dealing with. EPA recommends testing your water annually.

You should also test your well water if:

  • you recently repaired any part of your well, or 
  • there has been a change in the initial environmental conditions from land construction activities or flooding situations.

The Effects Of Sulfur-Smelling Well Water

An unpleasant smell from your well water can either be only of aesthetic concerns or both aesthetic and health concerns.

When in the air, hydrogen sulfide gas is flammable and poisonous, but when consumed with water it can cause diarrhea and dehydration after long periods of consumption.

It is vital to get your water source fully tested to detect the source of your sulfur smell, and find a solution as soon as possible.

Well water that smells like sulfur can

  • Give fabrics, plates and our bodies an unpleasant odor
  • Cling to clothing materials, leaving black stains on them
  • Darken silverware
  • Discolor utensils
  • Damage plumbing fixtures.

A more prominent effect of sulfur in water is that it provides a conducive environment for the growth of iron bacteria.

These are organisms that react with iron to form sticky, slimy, reddish brown deposits on different home appliances. They can cause corrosion in pipes, contaminate water with metal flakes and lead to cracks and leakages.

Iron bacteria can also block drainage systems and reduce the efficiency of water flow.

Is it safe to drink well water that smells like sulfur?

Small amounts of sulfur in drinking water are relatively harmless since most of the foods you consume frequently are rich in sulfur, including beef, turkey, eggs and chickpeas.

However, in large quantities or after prolonged consistent consumption, there is a risk of diarrhea and dehydration.

Also, the cause of the smell could determine how toxic the water could be to health. For instance, if there is environmental pollution, there may be an increased risk of gastrointestinal infections and other severe medical conditions.

It is safer to avoid the risk of jeopardizing your overall health and remove the source of sulfur from your well. Besides, the odor of the water (rotten eggs) is repelling enough to make anyone find a better alternative of water to drink.

Remember, if your well is the source of the sulfur smell (not the water heater) it is important to not expose yourself to the immediate well area or inhale the hydrogen sulfide gas.

While at low concentrations the effects are limited to respiratory and eye irritation, at moderate and high concentrations the effects include:

  • Headache
  • Dizziness,
  • Nausea
  • Vomiting
  • Staggering
  • Accumulation of fluid in the lungs
  • Shock
  • Convulsions
  • Inability to breathe
  • Unconsciousness
  • Coma and death

These symptoms can occur within just a few breaths, so please do not take any risks when treating your well.

How To Get Rid Of Sulfur Smell From Well Water

To remove the sulfur smell from well water, you must know the source of the odor. If the sulfur or rotten-egg smell is coming directly from the well then disinfection with a strong chlorine solution will kill the sulfur-reducing bacteria.

A licensed well contractor is recommended to ensure that all pre-disinfection tasks are carried out and that the appropriate respiratory protective equipment is worn.

If you decide to do this on your own, you can find a full guide on well disinfection in our related post ‘How To Quickly Get Rid Of Algae From Well Water’. Adhere strictly to all chemical, electrical and respiratory precautions clearly outlined.

If the source of the sulfur smell is from the water heater, you will require a professional unless you are fully confident in your knowledge of water heater operation and maintenance. There are three approaches to this. You could either:

  • Remove or replace the anode attached to the plug of the water heater. You could replace a magnesium anode with aluminum material to maintain corrosion protection without encouraging future hydrogen sulfide formation.
  • Disinfect and flush out the water heater using chlorine bleach solution. This should remove any sulfur bacteria generating the gas with the foul odor.
  • Increase the water heater temperature to 71 degree Celsius (160°F) for a few hours to kill the sulfur-reducing bacteria and then flush out the water.

However, increasing temperature on a water heater temperature can be dangerous. Be sure to check with the manual, manufacturer or dealer regarding the operable pressure relief valve, and any other recommendations. 

Be aware that these methods are better performed by plumbers or water system professionals to avoid damages, and to ensure your safety.

Will A Water Filter Remove Sulfur Smell From Water?

Water filtration systems can remove up to 90% of bacteria and their by-products from water, including hydrogen sulfide gas, the main cause of sulfur or rotten-egg smelling water.

These filters often have oxidizing, chlorination, ozonation, ion exchange, or activated carbon systems integrated, which either kills the causative organisms or exchange the sulfur ions for less toxic or less problematic ions.

We recommend the Epic Nano Water Filter Pitcher as an easy and affordable method of water purification that can remove bacteria. The Epic Nano is the ideal filter pitcher for well water, because it removes more than 200 contaminants as well as bacteria, parasites and viruses – and it is made in the USA.

If you would like to learn more about the Epic Nano, you can read this detailed review on the filter pitcher.


Asides from the odor, remember to pay attention to the health of your plumbing system, clothes and silverware, and to have a water testing routine. Small concentrations of sulfur can go unnoticed since they might not give off any foul odors. For convenience and to avoid forgetting, pick a testing date and make it an annual appointment on your calendar.

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