What you need to knowWater that is giving off a distinctive smell is most likely contaminated with hydrogen sulfide. Hydrogen sulfide, as it is also known, does not usually pose immediate health problems at the levels it is found in domestic drinking supplies. However, it is certainly an inconvenience — especially to one's nose. Being informed is always an important step in safety issues. What follows are answers to popular hydrogen sulfide questions. What is hydrogen sulfide, and how does it form?Sulfur-reducing bacteria present in ground water use sulfur as an energy source to chemically change sulfates to produce hydrogen sulfide. The bacteria uses sulfur from decaying plants, rocks, or soil. They exist in environments that are oxygen-deficient such as deep wells and plumbing systems. However, hydrogen sulfide can exist naturally in ground water as well. It can enter surface water through springs and quickly escape into the atmosphere. Hydrogen sulfide crops up other ways too. The magnesium rod used in water heaters for corrosion control can chemically reduce sulfates to hydrogen sulfide, and sewage pollution can be a source. How can hydrogen sulfide affect one's health?Hydrogen sulfide can be toxic, but its strong odor usually allows for detection long before it reaches extreme levels. Hydrogen sulfide is flammable and poisonous. Such concentrations are not common, but if the gas is released in a confined area it can cause nausea, illness, and—in extreme situations—death. What effects does hydrogen sulfide have on the environment?Hydrogen sulfide can be corrosive to metals such as iron, steel, copper, and brass, and it can cause yellow or black stains on kitchen and bathroom fixtures. It can discolor and alter the taste of beverages and food prepared with contaminated water. How can hydrogen sulfide be detected?The nose is the best source. Hydrogen sulfide is one of the few water contaminants that human senses can detect at low concentrations. The odor is most noticeable when water is first turned on or heated. Thus, a shower can be an unpleasant experience. The odor can be detected at levels as low as 0.5 parts per million. At less than 1 ppm, hydrogen sulfide will give water a musty odor. At 1 to 2 ppm, it will have an odor similar to rotten eggs. Levels are usually less than 10 ppm. Since hydrogen sulfide is dissolved in water and vaporizes from it, samples must be analyzed at the site or stabilized before sending them to a laboratory. Several test kits are available for less than $10. How can hydrogen sulfide be treated?There are various methods. They should be chosen based on the level of hydrogen sulfide, the amount of water being treated, the levels of iron and manganese, and bacterial contamination. Hydrogen sulfide can be reduced or removed by activated carbon filtration, shock chlorination, oxidizing chemical injection, oxidizing filtration, and water heater modification.
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