The presence of a sulfurous, rotten egg-like odor emanating from a washing machine typically indicates the proliferation of sulfate-reducing bacteria (SRB). These microorganisms thrive in dark, moist environments with limited oxygen, converting sulfates present in water and detergent into hydrogen sulfide gas, which is responsible for the unpleasant smell.
Addressing this issue promptly is important, as the odor can permeate clothing and the surrounding laundry area. Prolonged exposure to hydrogen sulfide, even at low concentrations, can be irritating and, in rare cases, corrosive to metal components within the washing machine. Identifying and mitigating the conditions that foster SRB growth will prevent recurrence and maintain a hygienic laundry environment.