Sulfur produces that distinct "rotten egg" odor and sulfate-reducing bacteria produce a slime and can promote the growth of other bacteria, such as iron bacteria. The slime can clog wells, plumbing, and irrigation systems. Bacterial slime may be white, grey, black, or reddish brown if associated with iron bacteria. Hydrogen sulfide gas in water can cause black stains on silverware and plumbing fixtures. It can also corrode pipes and other metal components of the water distribution system.
Hydrogen sulfide gas can result from a number of different sources. It can occur naturally in groundwater. It can be produced by certain "sulfur bacteria" in the groundwater, in the well, or in the water distribution system.
Sulfur in wells does not cause health problems, but can have the following unpleasant and possibly expensive effects: horrible odors, corrosion of plumbing and appliances, black stains and sulfur reducing bacteria problems.
Any level of sulfur is undesirable.