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Rotten Egg Odor From Water

Updated on April 8, 2015
Source: Wikimedia Commons
Source: Wikimedia Commons

Sulfur is found in two varieties in water, either hydrogen sulfide or sulfate. They are not causes of health hazards at the levels of concentration found in drinking water, but their foul odor of rotten eggs is a nuisance to people in their vicinity.

Oxygen and sulfur combine together to form sulfate. Groundwater always contains some elements of both since it lies trapped within rock bodies and topsoil where sulfur and oxygen are a part of their constituents. The various minerals within these formations get dissolved in the water over time, and in turn become its constituents.

Hydrogen sulfide is sometimes found naturally within water in the ground. It is primarily formed due to decomposition of vegetable matter, and the gas so formed ultimately permeates into the water. Bacteria that reduces sulfur to utilize as a source for their energy also releases hydrogen sulfide through a chemical process, and convert sulfates occurring naturally within the soil into gas. These bacteria survive in atmospheres that are oxygen deficient, and they can thus live in wells that are deep, pipes buried underground for plumbing, and heaters and softeners for water. They survive within the warmer portion of a water delivery system, and thus heating up the water sufficiently to eliminate the bacteria is a fallacy in the mind of many.

Hydrogen sulfide can also sometimes be formed within a water heater, giving the water a nasty rotten egg smell. The main reason for formation of hydrogen sulfide there is because of corrosion of the magnesium rod within the heater, which then reduces the sulfates within the stored water into hydrogen sulfide.



How does Sulfate Affect Drinking Water?

Minerals containing sulfates are normally found in groundwater that we use for drinking. These minerals cause scaling within the plumbing pipes over time. The sulfate from these minerals when released into the water can cause dysentery-like symptoms when consumed. It gives the water a bitter taste, and at times is unpalatable. When chlorine is used for bleaching clothes, cleaning gets to be a difficult chore with increased levels of sulfate in the water. Bacteria that oxidizes sulfur, convert the sulfide element within water into sulfate, producing a slime that over time can clog up pipelines and cause stains to clothes being washed. When toilet cisterns or tanks have water that has darkened, it is an indication that water inside them contains bacteria that oxidizes sulfur. Such bacteria are more commonly found than bacteria that reduces sulfur.


Source: Wikimedia Commons
Source: Wikimedia Commons

How does Hydrogen Sulfide Affect Drinking Water?

Hydrogen sulfide is associated with a rotten egg odor. It also changes taste of drinking water. It lies dormant and trapped within the water until the tap is turned on or water is warmed in the heater. Releasing water or heating it up causes the gas to mix in with air and get noticeable, otherwise they remain largely undetected. Heaters normally come with corrosion control in the form of magnesium rods. These rods reduce the sulfate in the water and convert it into hydrogen sulfide.

Hydrogen sulfide also corrodes steel, brass, copper and iron. It stains silver, and changes the color of brass and copperware. The gas occasionally affects toilet and kitchen fittings, and leave them with black or yellow stains. Foods cooked in water containing hydrogen sulfide may have an altered taste and appearance, as can beverages like tea and coffee.

When hydrogen sulfide is formed at a high concentration level in a softener for water that is based on ion exchange technology, it destroys the resin bed utilized to soften up the water over time. Such softeners create an environment for bacteria that reduce sulfate to thrive. Sometimes these bacteria survive on the salt present in water in a natural form, and utilize the sulfate contained within water for their energy requirements. Despite treating the water, if a hydrogen sulfide odor is still detected, it is evidence enough that the system contains these bacteria.


What are the Side Effects of Drinking Water that Contains Sulfates?

Sulfates tend to give a laxative-like effect to livestock and humans. This then leads to dehydration. Other than this side effect, sulfates really do not pose a health hazard, and if consumed over a period of time most people get used to it with effects if any disappearing. The bacteria that oxidizes sulfur to sulfate causes no risk at all to humans. However, the maximum permissible level for consumption is 250 mg/L, beyond which it may have some side effects.


Source: Wikimedia Commons
Source: Wikimedia Commons

What are the Side Effects of Drinking Water that Contains Hydrogen Sulfide?

Normally, hydrogen sulfide does not pose any health hazard at concentration levels found in potable water. The gas itself though is poisonous and extremely flammable. When hydrogen sulfide concentration level goes up in water and is released into the atmosphere, it is known to have caused various illnesses, sometimes nausea, and in some extreme cases even death.

Disease is normally not caused by hydrogen sulfide exclusively. There are times when pollution in sewage releases hydrogen sulfide sending out the rotten egg odor, and these instances need to be remedied as early as possible since they may cause diseases. Testing for contamination by bacteria at regular intervals is thus essential, if not for anything other than to determine if the plumbing lines for sewage have leaked and contaminated the drinking water pipeline.


Testing for Sulfate and Hydrogen Sulfide

There are various testing kits available for both sulfates and hydrogen sulfide. However, in the case of hydrogen sulfide, the laboratory that is testing the water needs to be informed in advance so that they send a container that will stabilize hydrogen sulfide in the gaseous form immediately after sample collection. Though trapped within the sampled water, hydrogen sulfide can escape, and containers need to have suitable preservatives to stabilize the sample immediately after collection.

For sulfates, the maximum allowable concentration level is 250 parts per million or 250 milligrams per liter. This falls in the category of secondary classification that constitute staining characteristics, taste, color, odor, foaming and corrosion power of the water. The primary classification is concerned with health hazards associated with the sample and include presence of radioactive minerals, chemicals that are toxic and pathogens.

Hydrogen sulfide is not required to be regulated by drinking water standard authorities since if it is present at a high level of concentration in water, it will anyway make it unpalatable. Water containing as less as 0.5 parts per million of hydrogen sulfide can be easily detected due to the presence of rotten egg odor. Water generally contains hydrogen sulfide below 10 parts per million, though some samples have been found to contain upwards of 50 parts per million at times.


Man-made water channel

Source: Wikimedia Commons
Source: Wikimedia Commons

What Can Be done to Eliminate Sulfate and Hydrogen Sulfide from Drinking Water?

There is nothing much that can be done to eliminate sulfates and hydrogen sulfide once it is present in drinking water. That's because drinking water sources are primarily groundwater, and checking dissolving minerals in that water is virtually impossible. Water treatment plants try their best to reduce the concentrations, but plumbing pipelines still carry some element of both. The bacteria contained within these closed spaces thrive and reproduce through the process of oxygen reduction. When sulfates and hydrogen sulfide are detected in drinking water at unbearable levels, there are basically two options left.

Follow your nose for that rotten egg smell!

The first option is to lay a new pipeline from the water source and install a new treatment system to purify water. This is an expensive mode for elimination, but required nonetheless if it causes paramount health risk as determined by a water treatment agency or a physician. In such cases, it is advisable to dig a well at a location further away from the present well or locate a suitable aquifer with either shallow or deep water body and then reinstall pipeline from these sources.

The second alternative is to purchase treated mineral water bottles from stores. However, that may not be economical for large families, and the former option needs to be investigated before opting for purchasing water from stores.

The third option is installing a new water treatment system in the house that treats all pipelines before getting into the tap for free flow. It is always preferable to have two treatment plants, one outside and the other inside the house. The outside plant treats water before it enters the hidden plumbing within the house, while the in-house plant treats the water once again before delivery to taps.


Treatment for Sulfate and Hydrogen Sulfide.

Sulfates can be treated through osmosis in reverse or distillation if used for cooking and drinking in relatively small amounts. When larger quantity of water needs to be treated, exchange of ions is the preferred choice in a treatment plant. Such plants contain a bed of resins, and when the sulfates are absorbed to saturation point by the resins, they need to be generated again through addition of salt water.

Distillation is another process through which sulfates can be eliminated. The process of distillation invloves vaprizing the water into steam. Steam does not carry minerals, and when cooled and recondensed, the water formed is devoid of any particulate matter.

Hydrogen sulfide on the other hand can be treated at the water source itself by disinfecting or chlorinating the water. If the rotten egg odor is found in a water heater system, replacing the magenesium rod that controls corrosion may be the right solution. Such rods are also available in alumunium, and replacing the rofd with another metal may get rid of the hydrogen sulfide and its associated foul odor.

A carbon filter may be used to eliminate hydrogen sulfide at low levels. At higher levels, oxidizing filters may be used. At still higher levels, adding potassium permanganate or bleaching powder and then filtering the water may be the solution.


Diagram of an artesian well / aquifer with an oasis in the desert

Source: Wikimedia Commons
Source: Wikimedia Commons

Conclusion

Hydrogen sulfide and sufates do not really pose any serious health risk when present in water at permissible concentrations. However, they have associated nuisance in the form of rotten egg smell, damaging clothes and utensils, and choking up pipelines.

If the rotten egg odor gets all pervasive, it is advisable to switch off the treatment system and drain it off water. The tank within the system may then be filled with water, but this time with a temperature setting of more than 140 degrees Fahrenheit. The tank needs to be maintained at this setting for the next six hours. After this duration, the tank temperature may be got down to normal and filled with water once again.

To treat groundwater, it is preferable to disinfect the source with shock treatment by using chlorine or potassium permanganate. If that is not possible or does not still solve the problem, digging a new well or locating an aquifer that is either shallow or deep yet contains sufficient water to supply water unhindered over a long period of time needs to be located.

It is always advisable to analyze water quality through a reputed agency and get it investigated at a state licensed laboratory. Depending on the concentration levels of sulfates and hydrogen sulfide in the water, suitable treatment systems may be installed, or if present in negligible amounts, can be overlooked since neither poses a serious health hazard to livestock or humans.

With special reference to the Yakima, Kittitas and Benton Counties of Washington State, issues related to the quality of water range from turbidity, sediments that are suspended, toxins and bacteria. Though the Kittitas and Yakima Valleys have an extensive and sophisticated network of canals, withdrawals from the canals and then returns leave the water quality impaired. This impacts the water and makes it unsafe to drink. Coupled with presence of sulfates and hydrogen sulfide present in large quantities, it is all the more reason to install suitable treatment plants wherever necessary, or replace existing pipelines to minimize the nuisance as far as possible. If that is not possible, withdrawals from the network of canals can be discontinued and fresh water sources located that can provide continuous water over a long span of time.

Rotten egg smell in home?

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    • Genna East profile image

      Genna East 2 years ago from Massachusetts, USA

      I have only smelled this "rotten egg" odor once, but I will never forget it. Thank you for this highly informative and interesting article.

    • FlourishAnyway profile image

      FlourishAnyway 2 years ago from USA

      When I was traveling through West Virginia I ran into this and decided not to drink the water even though the hotel claimed it was safe.

    • profile image

      Dip Mtra 2 years ago

      Yes Dana, it is quite horrible. I understand through research that people living in Yakima valley of Washington state are affected by this nuisance, though it is prevalent worldwide and can occur wherever groundwater is rich in sulfates.

    • Dana Tate profile image

      Dana Tate 2 years ago from LOS ANGELES

      I never had the experience of having or smelling water that smelled like rotten-eggs. I can imagine it is a horrible experience.