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How to deal with rotten eggs smell in water heaters

small-heat-logoOne of the possible issues with the water heaters is an unpleasant rotten eggs smell. This is caused by the sulfur found in water supplies. Sulfur in tap water can be in two forms: sulfate and hydrogen sulfide. Both do not pose any health risk at the concentrations usually found in tap water but they are nuisances because of the unpleasant smell. So, if your hot water smells like rotten eggs, there is no need to panic. You will be most certainly able to fix this issue on your own. Here’s what you need to know and what you have to do in order to get rid of it.

Sources of hydrogen sulfide and sulfate in water

Sulfates are a combination of oxygen and sulfur that are naturally occurring minerals in some rock and formations containing groundwater. The mineral is released into groundwater as it dissolves over time. Sulfur-reducing bacteria are using sulfur as their energy source. These bacteria produce large quantities of hydrogen sulfide by chemically changing the natural sulfates from the water to hydrogen sulfide. These bacteria prefer to live in oxygen-deficient environments such as water heaters, water softeners, plumbing systems, and deep wells. They can flourish in hot water.

Hydrogen sulfide is another gas that can also naturally occur in some groundwater, being formed from decomposing decaying pant material and other underground deposits of organic matter. Hydrogen sulfide can be found in deep or shallow wells drilled in sandstone or shale, or near oil fields or coal deposits. It can also enter surface water through springs.

The hot water heater can become occasionally a source of hydrogen sulfide odor. The naturally occurring sulfates can be reduced by the magnesium corrosion control rod to hydrogen sulfide.

Potential effects of sulfates and hydrogen sulfide in water

Sulfate minerals can cause building up scale in water pipes and may give a bitter taste in water. It may have a laxative effect on humans. Chlorine bleach in combination with elevated sulfate levels can make difficult cleaning clothes.

Hydrogen sulfide gas gives a “sulfur water” or “rotten egg” taste and odor in the water. Sometimes, this unpleasant odor may be noticeable only when hot water is run or when the water is initially turned on. The gas is forced into the air under the effect of the heat. This may cause the odor to become especially strong in a shower.

If your hot water heater is a source of an offensive hydrogen sulfide odor, this may also produce other nuisances such as corrosiveness to metals such as brass, copper, steel, and iron. It can discolor brass and copper utensils and tarnish silverware. Hydrogen sulfide also can cause black or yellow on bathroom and kitchen fixtures. Tea, coffee, and other beverages may be discolored and cooked food may have its taste affected if it is prepared with water containing hydrogen sulfide.

The resin bed of an ion exchange water softener can be contaminated by high concentrations of dissolved hydrogen sulfide. If the filtered or softened water had a hydrogen sulfide odor and no hydrogen sulfide can be detected in the non-treated water, this is a sign that indicates the presence of sulfate-reducing bacteria in the water treating system.

Potential health effects

As I was saying, sulfate may have a laxative effect in humans. This is of special concern for infants, since it can lead to dehydration. On the other side, hydrogen sulfide is poisonous and flammable. Fortunately, the level of hydrogen sulfide usually found in household water it is not a health risk. Very high concentrations are rare. In case that high concentration of hydrogen sulfide from the drinking water is released in confined areas, it may lead to illness, nausea, and in extreme cases even to death.

If your experience a rotten eggs smell in your water heater it is recommended testing for bacterial contamination with the Sulfate Reducing Bacteria. You may purchase a testing kit for the sulfate test that includes a questionnaire, instructions, and information on returning the sample.

Treatment options

If your water supply contains excessive hydrogen sulfide or sulfate, you have three options: use bottled water, an alternate water supply or use some type of treatment. If  we are talking about a wheel, you may drill a new one in a different location in order to obtain a satisfactory alternate water supply, you may purchase bottled water from stores or directly from suppliers, or you may install a whole-house water treatment system.

For sulfate there are available several methods of removing and treatment. The most suitable treatment method for you depends on factors including how much water you need to treat, the amount of manganese and iron in the water, the level of sulfate in the water, and also the bacterial contamination exists in your water. The typical methods for treating small quantities of water are reverse osmosis or distillation. For treating large quantities of water the most common method is ion exchange.

In case of hydrogen sulfide contamination this may be temporarily controlled by well disinfection or conducting a shock chlorination. If the problem occurs because of Sulfate Reducing Bacteria you may need a high level of chlorination and turbulence.

If the rotten eggs smell is primarily associated with the water heater, then you may need a hot water heater modification in order to reduce the odor. You may improve the situation by replacing the water heater’s magnesium corrosion control rod with one made of a different metal. A carbon filter may also work for removing low levels of hydrogen sulfide, while an oxidizing filter can remove high concentration of hydrogen sulfide.

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Hot water heater treatment

Here are the step by step instructions for a hot water heater treatment to reduce the rotten eggs smell:

  • Drain the system after turning it off.
  • Refill the tank and raise the temperature above 140 F.
  • Keep this water temperature in the tank for at least 6 hours.
  • Turn off the system and lower the temperature to normal levels.
  • Refill the tank again.

In case that you are using a well, it is recommended to show disinfect both the distribution system and the well. Since your treatment options depend on the quantities and form in which hydrogen sulfide and sulfate occur, it is better to perform a comprehensive water analysis first.

Final words

small-heat-logoFinally, I hope I’ve brought some light over this subject. Remember, the very least you can do yourself is to follow the 5 steps presented in the section above and to change the corrosion rod before calling in a specialist. If you have any other advice or if you have questions, I would love to hear from you.

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