Smelly Water - State Water Heaters RESIDENTIAL ELECTRIC WATER HEATER Service Handbook

TECHNICAL BULLETIN
BULLETIN 22
The most common cause of "smelly water" is a non-toxic sulfate reducing bacteria,
CAUSE
scientifically termed Divibrio Sulfurcans. This bacteria often enters the water system
through construction or a break in ground piping. The bacteria create the energy it
needs to survive by converting sulfate (SO
the water.
Hydrogen sulfide gas is distinctive because of its rotten egg-like stench. Its presence
can severely affect the taste as well as the odor of the water. Occasionally this
bacteria can be accompanied by black deposits, the result of pipe and fitting corrosion.
In extremely high concentrations, hydrogen sulfide gas can be toxic though the gas is
detectable long before harmful levels are reached.
The requirements for the bacteria to thrive are: a) an elevated level of sulfur in the
water, b) activated hydrogen from cathodic reactions within the tank, c) water with little
or no dissolved oxygen, d) and temperatures below 138°F.
Items that can increase the potential for this bacteria are: a) water softeners, b) well
water, c) and long periods of no water movement.
Other factors that may contribute to smelly water:
The simplest treatment available is the shock-chlorination of the system. This is a
TREATMENT
surface treatment, and often requires repeated trials in heavily infected systems. The
chlorination of a system requires that you follow each step explicitly to avoid an un-
treated portion of the piping system from reinfecting another part. See Bulletin 23 for
the chlorination procedure. Longer lasting solutions include chlorination or aeration of
the water supply.
NOTE Since smelly water is caused by a bacteria presence and is not caused by the water
heater, any treatment would not be considered warranty related.
The chlorination procedure is used to eliminate various bacteria that accumulate and
CAUSE
grow in water heaters. These bacteria often cause odorous or discolored water
conditions.
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Technical Training Department
Ashland City, Tennessee ©2004
RESIDENTIAL ELECTRIC WATER HEATER
SERVICE HANDBOOK

SMELLY WATER

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Chlorides of Magnesium and Calcium leave a bitter taste.
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Chloride of Sodium produces a salty taste.
•
Sulfates (50 ppm) give a medicinal taste.
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Carbon Dioxide in a low pH water gives fizzy water.
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Iron and tannic waters also give a bad taste and odor.
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) to hydrogen sulfide (H
4
Residential Electric Svc Handbook
S) gas you smell in
2
STC082