Sulfides are commonly present in wastewaters, partly from the decomposition of organic matter. Gaseous H2S is very toxic in closed areas. At levels toxic to humans it interferes with the olfactory system, giving a false sense of safe absence of H2S. It attacks metals and has caused serious corrosion of concrete sewers.
Acceptable results: There is no health standard. The threshold odor concentration of H2S in clean water is between 0.025 and 0.25 ppb.
Sources: Naturally in hot springs but most commonly present in wastewater from industrial sites.
Recommended testing: If water has bad odor (rotten egg) or suspect hydrogen sulfide in water system.
