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Two often cited objections to the use of sodium hypochlorite for
buildingwater systemdisinfection are 1) doubts about performance above
pH 8 and 2) corrosion. However, aswas shown in this study and inmany
others, microbial control with chlorine is quite practical, effective and
extraordinarily inexpensive compared to all other alternatives even above
pH8andhighalkalinity.Corrosionofpremiseplumbing isnegligibleatuse
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
oftengive commercially conflicted recommendations that are scientifically
indefensible.
HazardControl inUtilityWaterSystems
There isnotechnicalexcuseforanHVACcoolingtowertobe ladenwith
Legionella
. Properapplicationof cooling towerbiocidesandeffectiveuseof
inhibitors to control scaling and corrosionhave been shown to adequately
control
Legionella
in these systems.Themost extensive surveys of cooling
towers in theUS (Miller 2006) indicate that less thandetectable
Legionella
arepresent in thevastmajority (about90%).Therefore,microbial control is
unacceptable inonly about 1of 10 cooling towers in theUS.The challenge
is to identify those systems and correct themicrobial control programs in
them.
Non-oxidizing biocides and expensive (but certainlymore profitable)
“stabilized” oxidizing biocides are preferentially marketed as superior to
sodium hypochlorite for cooling towers programs. These products are
