Hydrogen sulfide (H2S) is a colorless, flammable gas. H2S gas is also called sewer gas, sour gas or stink damp.
Hydrogen sulfide gas occurs naturally in ground water. The presence of hydrogen sulfide can be a result of a number of sources, such as:
- Decomposing deposits of organic matter
- Wells drilled in shale, sandstone, or near coal or peat deposits
- Sulfur-reducing bacteria that feed on naturally occurring sulfates in water, producing the hydrogen sulfide gas. While a nuisance, sulfur-reducing bacteria do not present any known human health risk.
- Water heaters with magnesium rods. The rods reduce the naturally occurring sulfates to hydrogen sulfide.
- In rare cases, the gas may be a result of sewage or other wastewater pollution. It is recommended that a coliform bacteria test also be performed.
Hydrogen sulfide gas produces an offensive “rotten egg” or “sulfur water” odor and taste in water. The odor is noticeable when water is initially turned on or when hot water is running. Heat forces the hydrogen sulfide gas into the air. Most people can detect hydrogen sulfide in water by taste at concentrations as low as 0.05 ppm (mg/l) and by smell at concentrations as low as 0.1 ppm. Some people can become used to both the odor and taste of hydrogen sulfide in water as high as 6 ppm. Those that are not accustomed to sulfur water find it very unpleasant.
Water supplies with concentrations of 1.0 ppm of hydrogen sulfide may be corrosive to iron, steel, copper, and brass. It can tarnish silverware and discolor copper and brass utensils. It can also cause yellow or black staining on kitchen and bathroom fixtures. It can also affect the taste of cooked foods and beverages (such as coffee and tea). Higher concentrations of hydrogen sulfide may foul the resin bed of an ion exchange water softener. HEALTH EFFECTS
No health effects have been found in humans exposed to typical environmental concentrations of hydrogen sulfide (0.00011– 0.00033 ppm) in air. Very little information is available about health problems that could occur from drinking or eating something with hydrogen sulfide in it. Scientists have no reports of people poisoned by such exposures. Hydrogen sulfide has not been shown to cause cancer in humans.
Hydrogen sulfide gas can irritate the eyes, nose and throat. Eyes may become watery, red and itchy. Exposure to H2S can also cause headaches, nausea (upset stomach), fatigue (feeling tired), shortness of breath, chest pain and other health-related symptoms. Brief exposures to high concentrations of hydrogen sulfide in air (greater than 500 ppm) can cause a loss of consciousness.
Most people can smell H2S at levels much lower than the levels that can cause these health effects. Just because you smell H2S, does not always mean you will experience adverse (bad/negative) health effects. However, sensitive populations, infants, young children, the elderly, people with asthma or other respiratory problems and people with heart problems may be more likely to experience these symptoms and negative health effects from exposure to H2S.
Hydrogen Sulfide (H2S)
ACTION IS RECOMMENDED
The levels of hydrogen sulfide detected in your water are higher than the concentration level of 0.1 parts per million (ppm) recommended by the Ohio Department of Health. Drinking water treatment should be considered at this concentration.
At this concentration, you should be able to taste and smell the hydrogen sulfide in the water. The taste may affect hot beverages such as coffee, tea, and other cooked foods. The odor may be more noticeable when first running or heating the water. It may be unpleasant when showering. Metals such as iron, steel, copper, and brass may show signs of corrosion at concentrations as low as 1 ppm.
Smelling hydrogen sulfide does not always mean you will experience adverse (bad/negative) health effects. Since most people can smell hydrogen sulfide at levels much lower than the levels that can cause the health effects, a laboratory test is not necessarily needed to detect its presence in air; however, a test is recommended to determine the amount of hydrogen sulfide in the water.
- ATSDR - Toxic Substances Portal - Hydrogen Sulfide
- Michigan Department of Environmental Quality - Hydrogen Sulfide (H2S) - Q&A
- Penn State Extension - Hydrogen Sulfide (Rotten Egg Odor) in Water Wells
- Purdue University Cooperative Extension Service - Sulfur Water Control (Rotten Egg Odor in Home Water Supplies)
- Ohio Department of Health - Health Assesment Fact Sheet - Hydrogen Sulfide (H2S)
- ATSDR ToxGuide - Hydrogen Sulfide
- ATSDR ToxFAQs Fact Sheet - Hydrogen Sulfide
- Water Systems Council - wellcare® information for you about Sulfur & Groundwater
- Texas Agriculturel Extension Service/Texas A&M University - Hydrogen Sulfide in Drinking Water Causes and Treatment Alternatives
- Virginia Cooperative Extension - Virginia Household Water Quality Program: Sulfate and Hydrogen Sulfide in Household Water
- University of Georgia Extension - Hydrogen Sulfide and Sulfate and Removal of Hydrogen Sulfide and Sulfate