A.O. Smith GPVL-50 Service Handbook page 32

SYMPTOMS Rusty, brown, black, or yellow water appearing in the hot water.
CAUSES The most common cause of "smelly water" is a non-toxic sulfate reducing bacteria, scientifi cally
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
to hydrogen sulfi de (H
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 fi tting
corrosion. In extremely high concentrations, hydrogen sulfi de gas can be toxic though the gas is
detectable long before harmful levels are reached.
The requirements for the bacteria to thrive are:
• Elevated levels of iron and manganese in the water.
• Water with little or no dissolved oxygen.
• Temperatures below 138°F.
Items that can increase the potential for this bacteria are:
• Water softeners.
• Well water.
• Long periods of no water movement.
Other factors that may contribute to smelly water:
• Chlorides of Magnesium and Calcium leave a bitter taste.
• Chloride of Sodium produces a salty taste.
• Sulfates (50 ppm) gives a medicinal taste.
• Carbon Dioxide in low pH water gives fi zzy water.
• Iron and tannic waters also give a bad taste and odor.
TREATMENT The simplest treatment available is the shock-chlorination of the system. This is a 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 untreated portion of the piping system from re-infecting
another part. See the "Chlorination Procedure" section. Longer lasting solutions include chlorination
or aeration of the water supply.
NOTES Since rusty water is caused by a bacteria presence and is not caused by the water heater, any
treatment would not be considered warranty related.
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SMELLY WATER
S) gas you smell in the water. Hydrogen sulfi de gas is distinctive because
2
)
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