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Two often cited objections to the use of sodium hypochlorite for
building water system disinfection are 1) doubts about performance above
pH 8 and 2) corrosion. However, as was shown in this study and in many
others, microbial control with chlorine is quite practical, effective and
extraordinarily inexpensive compared to all other alternatives even above
pH 8 and high alkalinity. Corrosion of premise plumbing is negligible at use
concentrations of sodium hypochlorite when the application is properly
controlled (Cantor 2003 and 2006).
Therefore, Water Management Teams must beware of chemical and
device vendors who are biased against use of sodium hypochlorite and
often give commercially conflicted recommendations that are scientifically
indefensible.
Hazard Control in Utility Water Systems
There is no technical excuse for anHVAC cooling tower to be ladenwith
Legionella
. Proper application of cooling tower biocides and effective use of
inhibitors to control scaling and corrosion have been shown to adequately
control
Legionella
in these systems. The most extensive surveys of cooling
towers in the US (Miller 2006) indicate that less than detectable
Legionella
are present in the vast majority (about 90%). Therefore, microbial control is
unacceptable in only about 1 of 10 cooling towers in the US. The challenge
is to identify those systems and correct the microbial control programs in
them.
Non-oxidizing biocides and expensive (but certainly more profitable)
“stabilized” oxidizing biocides are preferentially marketed as superior to
sodium hypochlorite for cooling towers programs. These products are
