Hydrogen sulfide gas produces an offensive "rotten egg" or "sulfur
water" odor and taste in the water. In some cases, the odor may be
noticeable only when the water is initially turned on or when hot water
is used. Heat forces the gas into the air which may cause the odor to
be especially offensive in a shower.
One of the many troubles with hydrogen sulfide is its strong corrosiveness
to metals such as iron, steel, copper and brass. It can tarnish
silverware and discolor copper and brass utensils. Hydrogen sulfide
also can cause yellow or black stains on kitchen and bathroom fixtures.
Coffee, tea and other beverages made with water containing hydrogen
sulfide may be discolored and the appearance and taste of cooked foods
can be affected.
High concentrations of dissolved hydrogen sulfide also can foul the
resin bed of an ion exchange water softener. When a hydrogen sulfide
odor occurs in treated water (softened or filtered) and no hydrogen
sulfide is detected in the non-treated water, it usually indicates the
presence of some form of sulfate-reducing bacteria in the system. Water
softeners provide a convenient environment for these bacteria to grow.
A "salt-loving" bacteria that uses sulfates as an energy source may
produce a black slime inside water softeners.
Sulfur-reducing bacteria, which use sulfur as an energy source, are the
primary producers of large quantities of hydrogen sulfide. These
bacteria chemically change natural sulfates in water to hydrogen
sulfide. Sulfur-reducing bacteria live in oxygen-deficient environments
such as deep wells, plumbing systems, water softeners and water
heaters. These bacteria usually flourish on the hot water side of a
water distribution system.
Hydrogen sulfide gas also occurs naturally in some groundwater. It is
formed from decomposing underground deposits of organic matter such as
decaying plant material. It is found in deep or shallow wells and also
can enter surface water through springs, although it quickly escapes to
the atmosphere. Hydrogen sulfide often is present in wells drilled in
shale or sandstone, or near coal or peat deposits or oil fields.
Occasionally, a hot water heater is a source of hydrogen sulfide odor.
The magnesium corrosion control rod present in many hot water heaters
can chemically reduce naturally occurring sulfates to hydrogen sulfide.