The presence of a rotten egg odor in potable water typically indicates the presence of hydrogen sulfide gas. This gas can occur naturally or be a byproduct of bacterial activity within a water system. The concentration required for detection by smell is very low, meaning even a small amount can be noticeable.
Understanding the source of this odor is essential for ensuring water quality and mitigating potential health concerns, although the gas itself is often more of a nuisance than a direct health risk at typical concentrations found in residential water systems. Long-term exposure to contaminated water can lead to plumbing corrosion, staining of fixtures, and potential bacterial contamination.