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

[pat.costner@dialb.greenpeace.org]

Yes, residual chlorine in drinking water distribution systems has 
long been regarded as necessary as a safeguard against  
pathogens that may enter the system via infiltration.  However, from 
the earliest days,  this strategy has been questioned.  As noted in 
the abstract of the recently published paper cited below,  

    "... the maintenance of a free residual concentration in a
    distribution system does not provide a significant inactivation
    of pathogens, could even mask events of contamination of the
    distribution, and thus would provide only a false sense of
    safety with little active protection of public health." 

I.e., pathogen infiltration into water distribution systems is 
an engineering problem and, as such, can and should be solved by 
proper construction and maintenance.

Best regards,

Pat Costner


--------------------------

Payment, P. 1999. Poor efficacy of residual chlorine disinfectant in 
drinking water to inactivate waterborne pathogens in distribution 
systems. 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. When sewage was 
added to the water samples, indigenous thermotolerant coliforms 
were inactivated only when water was obtained from sites very 
close to the treatment plant and containing a high residual chlorine 
concentration. Clostridium perfringens was barely inactivated, 
suggesting that the most resistant pathogens such as Giardia 
lamblia, Cryptosporidium parvum, and human enteric viruses would 
not be inactivated. Our results suggest that the maintenance of a 
free residual concentration in a distribution system does not 
provide a significant inactivation of pathogens, could even mask 
events of contamination of the distribution, and thus would provide 
only a false sense of safety with little active protection of public 
health. Recent epidemiological studies that have suggested a 
significant waterborne level of endemic gastrointestinal illness 
could then be explained by undetected intrusions in the distribution 
system, intrusions resulting in the infection of a small number of 
individuals without eliciting an outbreak situation. 


On 7 Jan 00, at 22:34, superjicb wrote:
Re: [Dioxin-l] "normal background level"

From:           	"superjicb" <superjicb@email.msn.com>

> Jon,
> 
> Look again and you will see that I did not suggest primary or secondary
> water treatment with chlorine, only residual water treatment -- that is
> the water that is already treated and clear that moves from the water
> treatment facility to your tap on the date that you personally decide to
> use it,  and it only takes a tiny bit of chlorine to accomplish what is
> needed.  Ozone and hydogen peroxide dissipate too fast to make it to your
> tap. Trust me on this one.  You only need chlorine for residual water
> treatment.   Also we can not always fall back on safe and effective
> remedies herbal remedies. Believe me this will not fly.  Do not advocate
> this.  Environmental advocates should not promote it if they want to be
> effective.  Chlorine and chlorine derivatives are sometimes needed.  So
> what! This is only a small total amount of the chlorine used today.  I'm
> only advocating that you accept a small amount of chlorine use.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Pat Costner
Greenpeace
P.O. Box 548
 or 512 County Road 2663
Eureka Springs, Arkansas 72632
ph: 1 501 253 8440
fx: 1 501 253 5540
em: pat.costner@dialb.greenpeace.org
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~