The Effect of Sulfur on Water

The last thing most of us expect when turning on the water tap is to be greeted by the smell of rotten eggs. It's especially troubling when taking a shower. Sulfur in water, while not a pleasant occurrence, is not usually a cause for concern and there are measures you can take to reduce or eliminate the unpleasant smell.

How does sulfur get into water?

• Drinking water in some parts of the United States contains sulfur in the form of sulfates, a chemical combination of the two elements sulfur and oxygen, giving the water a characteristic rotten egg smell. Sulfates get into water when it flows through soil with large quantities of organic matter containing sulfates or percolates through rock layers containing iron pyrite, a mineral composed of iron and sulfur. In some areas of the country, where there are large deposits of coal or petroleum, ground water picks up sulfur compounds from these minerals.

What happens to sulfur in water?

• Naturally occurring bacteria, called sulfur reducing bacteria, use sulfur compounds as a source of energy. In the process of extracting energy from sulfates, hydrogen sulfide gas is produced, the source of the rotten egg smell. Sulfur reducing bacteria don't need oxygen, so are commonly found in low oxygen environments like deep wells, water pipes, hot water heaters and water softeners.

Is sulfur in water harmful?

• Sulfates present in drinking water can have a laxative effect on people and animals. Over time, both animals and people become accustomed to sulfates in the water and are no longer bothered by them. Hydrogen sulfide is a poisonous gas, but is not usually present in drinking water in dangerous concentrations. In some cases, the presence of hydrogen sulfide gas can indicate contamination of the water supply by sewage. For this reason, it is a good idea to have your water tested for fecal bacteria if hydrogen sulfide is present.

Testing for sulfur in drinking water

• Most states have water testing laboratories and provide kits with which to take water samples. It is important when requesting a kit to let the laboratory know they will be testing for sulfur, as a preservative must be used in such cases to prevent the hydrogen sulfide gas dissolved in the water from escaping before it can be tested. Since the odor in the water can come from many sources, it is also important the questionnaire sent with the kit be filled out accurately to help the testing laboratory determine the correct cause of the problem.

Treating sulfur in drinking water

• The solution may be as simple as shock treating wells with chlorine to kill sulfur reducing bacteria. Other options include getting water from another source, the use of bottled water or installing a water treatment system. Water treatment systems typically treat the entire water supply to the home. In the long run, this alternative may be less expensive than bottled water or drilling a new well. Of course, if the smell doesn't bother you, the least expensive option is to ignore it.