Woman drinking water

Water Smell Like Rotten Eggs? Countertop Water Filter to the Rescue

Often drinking water has a particular taste and smell due to chemicals and other contaminants present in it. The "Rotten Egg" smell in household water might be caused by hydrogen sulfide gas produced by sulfur-reducing bacteria.

Usually, the odor-producing bacteria lives in aquifer soil, and itself does not indicate a health risk. However, the presence of such bacteria could mean that disease-causing bacteria is also present. Therefore the rotten egg smell in the drinking water should not be ignored but investigated further.

Hydrogen sulfide gas

The presence of the sulfur "rotten egg" smell is easily recognizable by its unpleasant odor. The smell is caused by hydrogen sulfide gas in the drinking water. The gas itself does not have any health risks, but in high concentration, the taste of the water can be very unpleasant and distracting.

How the smell occurs 

How Rotten Egg Smell Occurs

How Rotten Egg Smell Occurs

The Hydrogen sulfide gas produced by the bacteria (also called sink gas or sewer gas) remains trapped underground within sewage pipes. When the water is released to the surface, the gas escapes and becomes easy to smell. The smell can only be sensed when the hot water is running or when the tap is turned on for some time. Therefore, the smell is especially noticeable in the shower, as heat tends to help and force the hydrogen sulfide gas out. Many people can sense the odor of hydrogen sulfide even with a concentration as little as 0.5 ppm.


Although the bacteria itself is not proven to cause any health risks, the produced gas has a laxative effect that can also cause dehydration. Hydrogen sulfide gas can be poisonous and flammable in high concentrations. When is it released in closed spaces such as a shower, it is possible for the gas to reach a level high enough to cause illness or nausea. In very extreme cases it can have fatal outcomes. (R). Hydrogen sulfide can also discolor copper ware, silverware and brassware, stain laundry fixtures, discolor beverages, and change the taste and appearance of cooked foods.

Removal of hydrogen sulfide

The appropriate treatment to remove the gas depends on the gas concentration but treatment does not limit the level of sulfur in the water,or the amount of manganese and iron present in the water.

Continuous chlorination and filtration

This form of treatment of hydrogen sulfide is the most common. A chlorine chemical is used to turn the dissolved gas into another form of sulfur that is easily filtered from the drinking water. This treatment can efficiently remove any level of hydrogen sulfide but is mostly used when the concentration of gas exceeds 6.0 mg/L.

Oxidizing filters

These filters can remove up to 2-3mg/L of hydrogen sulfide. It can filter and oxidize the gas at the same time. The filter is made with potassium permanganate to create a coating that oxidizes the gas. The filter unit needs more than the regular amount of backwashing and regeneration as the concentration of hydrogen sulfide increases. For more information on how oxidizing filters works, check out this video. (R) (R).

Carbon filtration

Carbon Filtration

Carbon Filtration

Activated carbon filtration is efficient when the concentration level of hydrogen sulfide is below 1.0 mg/L. Besides soaking in the hydrogen sulfide gas, the filter also removes various water contaminants.

Catalytic carbon works similarly to the oxidizing filter, absorbing the gas first. It can treat the water at much higher hydrogen sulfide concentrations than activated carbon.


The aeration method has an advantage because it does not require the adding of chemicals to the water. It removes the gas by injecting air into the water and allowing the gas to escape. Aeration units work by stripping, bubbling, and cascading the hydrogen sulfide from the water. This method is usually used when the concentration level does not exceed 2 mg/L, as it cannot remove all the odor at higher concentration levels. (R). 

For more details about the water aeration process, check out his video.


The "Rotten Egg" smell in water often occurs due to harmless bacteria producing hydrogen sulfide that is living in the water system. To get rid of ths]is smell check out his article Best Countertop Water Filter Comparison – Review the Top Rated Purifiers.The bacteria itself does not indicate any health risks, but the odd taste and smell of the water is disturbing and should not be ignored. Fortunately, the presence of the gas can be detected at low concentration levels. The type of treatment mostly depends on the concentration level. The gas can be eliminated by the continuous chlorination and filtration methods, oxidizing filters, carbon filtration, and aeration.

References And Recommended Reading

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