[Dioxin-l] Re: Poor efficacy of residual chlorine in drinking water distribution

[david bell]

If I read the abstract below correctly, E coli is inactivated by residual 
chlorine throughout the distribution system. Given that E coli is a 
principal contaminant of sewage (and in turn the water supply system), and 
can be highly pathogenic (eg E coli 0157), this abstract can easily be used 
to make a case for chlorination of water supplies.

I am not sure what to make of the abstract; viruses can be very difficult to 
kill, and (I believe) some clostridia have a spore, again making them very 
difficult to disinfect. I don't know that E coli isn't a much more 
representative bacterial pathogen than the others this abstract measures.

david bell

Payment, P. 1999. <snip>Can J Microbiol 45(10):709-15
Abstract
To evaluate the inactivating power of residual chlorine in a
distribution system, test microorganisms (Escherichia coli,
Clostridium perfringens, bacteriophage phi-X 170, and poliovirus
type 1) were added to drinking water samples obtained from two
water treatment plants and their distribution system. Except for
Escherichia coli, microorganisms remained relatively unaffected in
water from the distribution systems tested.
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