The presence of a sulfurous odor in potable water, reminiscent of decaying eggs, typically indicates the presence of hydrogen sulfide (HS). This gas, even in trace amounts, is readily detectable by the human olfactory system. It results from the anaerobic breakdown of organic matter or can be produced by certain sulfur-reducing bacteria. The bacteria thrive in oxygen-deficient environments, often found in wells, plumbing systems, and water heaters.
The detection of this characteristic odor is a signal that warrants investigation. While low concentrations of hydrogen sulfide may only affect water’s palatability, higher concentrations can corrode metals like iron, steel, copper, and silver, leading to plumbing damage and potential staining of fixtures and clothing. Moreover, while often a nuisance rather than a direct health hazard at typical household levels, the presence of sulfur-reducing bacteria can sometimes indicate other underlying water quality issues.