There has been a great deal of research into the effects
of copper-silver ionization of water on a variety of bacteria and other
infectious agents. ThomsonTec makes no medical or scientific claims, but
provides the following data for informational purposes only.
For more detailed information about silver and its
applications to health, preventing disease outbreaks, and reducing or
replacing the need for chlorine,
Microbiological Evaluation of Copper:
Silver Disinfection Units
AUTHORS: Kutz SM,
Landeen LK, Yahya MT, and Gerba CP
PUBLICATION: Proceedings of the
Fourth Conference on Progress in Clinical Disinfection. State University
of New York, Bighamton, New York, April 11-13, 1988
Although chlorination is the traditional method
of disinfecting swimming pools, hot tubs, and cooling towers to prevent
outbreaks of illness due to pathogenic bacteria, viruses, and protozoa,
high levels of chlorine can cause eye and skin irritation was well giving
rise to a noticeable chlorine odor. The authors evaluated electrolytically
generated copper: silver ions alone and in combination with low levels of
free chlorine as an alternative method of reducing the bacterial
population in water.
MATERIALS AND METHODS:
The test medium was local well water which was subjected to chemical
analysis, filtering, and pH stabilization and used at room temperature.
Suspensions of the following organisms were prepared: Escherichia coli,
Legionella pneumophila, Staphylococcus aureus, Pseudomonas aeruginosa,
Salmonella TYPHII, Klebsiella terrigena, and Streptococcus faecalls.
Approximately 1 ml of the selected bacterial suspension was added to 99 ml
of test medium containing (1) copper: silver ions in a concentration of
400 ug/liter copper to 40 ug/liter silver, (2) free chlorine (0.2
mg/liter) alone, or (3) a combination of copper: silver ions and free
chlorine (quantities as above). Cultures were incubated and the bacterial
colonies enumerated, after which statistical analysis were performed.
The bacteria tested were inactivated more
rapidly in a solution in which electrolytically generated copper and
silver ions were added to low levels of chlorine than where either method
was used separately. Some organisms were more resistant to treatment than
others. In the experiments with Salmonella typehi and Klebsiella terrigena
no viable cells were recovered after 30 seconds of exposure to either
chlorine alone or to the combined regimen, indicating equal effectiveness
when resistance to disinfection is low. On the other hand, Legionella
pneumophilia titers decreased more than 5 log 10 values after 7 minutes of
exposure to free chlorine (0.2 mg/liters) alone for the same length of
time. Similarly, E. coli numbers were reduced by 4.2 log 10 by the
combination regimen but by less than 3 log 10 after extended exposure to
the copper: silver method without chlorine.
The use of electrolytically generated copper
and silver ions in combination with low levels of free chlorine proved an
effective method of killing a wide range of pathogenic bacteria under
controlled test conditions. Such bacteria are of potential concern in
swimming pools and cooling towers.
Inactivation of Poliovirus &
Bacteriophage MS-2 by Copper/Silver and Reduced Levels of Free Chlorine
Landeen LK, Yahya MT, and Gerba CP
Publication information not available
Viruses tend to be more resistant than bacteria to disinfection regimes.
Although chlorination is widely used to control viral contamination, high
levels of chlorine promote the formation of organic compounds in water
that may be hazardous to human health. An alternative method, copper and
silver ion treatment, is known to be effective against bacteria and algae.
The authors tested electrolytically generated copper and silver ions,
alone and in the presence of reduced levels of free chlorine, in treating
water sample to which either bacteriophage MS-2 or poliovirus had been
added to test effectiveness against viral contamination.
Purified bacteriophage MS-2 and poliovirus type I were prepared by
standard methods in pellet form. The viral pellets were placed in samples
of filtered well water. The virus-containing samples were then exposed to
one of the following treatment regimens: (1) no added disinfectant, i.e.
untreated control; (2) low levels of free chlorine; (3) a combination of
copper: silver with free chlorine; (4) copper: silver ions without
chlorine; or (5) either copper or silver without chlorine. Experiments
were performed in duplicate at room temperature. Linear regression
analysis was performed to calculate the viral inactivation rates for each
The bacteriophage MS-2 inactivation rate for copper alone was
significantly higher when the concentration reached 400 ug/liter. The MS-2
inactivation rate for electrolytically generated copper and silver ions
together was greater than for either metal alone, suggesting an additive
effect. Although not significant for very low levels of chlorine, the
addition of 0.3 mg/liter of free chlorine to a 400/40 ug/liter
copper/silver regimen significantly enhanced MS-2 inactivation rates.
Similarly for poliovirus, the activation rates achieved with the 400/40
copper/silver regimen were significantly greater as compared with
untreated controls. The number of poliovirus were reduced approximately
2.5 log 10 within 72 hours. The addition of 0.3 mg/liter of free chlorine
again improved the inactivation rates achieved, although in this case the
improvement did not reach statistical significance. Poliovirus showed
greater resistance to inactivation by any means tested than did
Electrolytically generated copper and silver ions demonstrate efficacy
against bacteriophage MS-2; further improvement occurs with the addition
of reduced levels of free chlorine. The same regimen is capable of
inactivating an enteric virus such as poliovirus in the presence or
absence of free chlorine. The same regimen is capable of inactivating an
enteric virus such as poliovirus in the presence or absence of free
chlorine. Therefore, a regimen in which copper: silver ion treatment is
combined with low levels of chlorine should prove useful as a method of
disinfecting water against viral contamination.
US SURVEY OF HOSPITALS
USING COPPER-SILVER IONIZATION FOR THE CONTROL OF LEGIONELLA
September 26-29, 2000,
Janet E. Stout, Y.E. Lin, V.L. Yu
VA Medical Center, Pittsburgh, PA
the University of Pittsburgh, Pittsburgh, PA
of its efficacy in numerous hospitals, the long term efficacy of
copper-silver ionization for controlling Legionella pneumophila in
hospital water distribution systems has not been well documented. We
conducted a survey of the first 13 hospitals in the U.S. that had
implemented copper-silver ionization systems on their hot water systems
for Legionella control. The mean bed size was 434 (range 150-700), 61%
(8/13) performed transplant operations. 100% (13/13) had diagnosed cases
of nosocomial Legionnaires' disease (LD). 30% of the hospitals installed
copper-silver ionization because of problems and expense associated with
the prior use of hyperchlorination. 50% had previously used thermal
eradication. The average number of ionization flow cells installed per
hospital was 3.4 (range 1-7), and the average start-up cost was $86,432.
46% (6/13) of hospitals had >30% of distal outlets positive before using
ionization, and 0% had > 30% positive after installation. For 46% (6/13)
of the hospitals, distal site positivity decreased to 0% positivity. When
we conducted the survey, the ionization systems had been in place from 1
to 4 years. Ionization requires regular maintenance and the pH of water
should be < 8.0 for optimal performance. Ionization is a viable option for
controlling Legionella in hospital water distribution systems.
5th International Conference on Legionella
September 26-29, 2000, Ulm, Germany
Infectious Disease Section,
University Drive C
Pittsburgh PA 15240USA
Bacteria In Water Systems by Using Electrolytically Generated Copper:
Silver & Reduced Levels of Free Chlorine
AUTHORS: Yahya MT, Landeen LK,
Mesina MC, Kutz SM, Schultze R, & Gerba CP
PUBLICATION REF: Canadian Journal of
Microbiology 36: 109-116, 1990
The recommended minimum level of free chlorine for disinfection of public
swimming pools is 1 mg/liter. This level is difficult to maintain due to
the chlorine-demanding organic material introduced by bathers themselves
as well as the environment. Eye and skin irritation may also occur at the
minimum chlorine level needed for effective disinfection. Electrolytically
generated copper/silver ions are also microbiocidal and are much less
subject to degradation but are slower acting than chlorine. Therefore, the
authors tested the hypothesis that using the two methods together would
accomplish effective disinfection while reducing the level of free
MATERIALS AND METHODS:
Two 32-gallon plastic containers, one indoors (temperature range 22 to 25)
and the second outdoors exposed to sunlight (temperature range 18 to 36)
were filled with tap water. After chemical analysis and adjustment of pH
and test levels of disinfectants, bath water and urine were added to
stimulate typical swimming conditions. Four treatment regimens were
tested: (1) No added disinfectants (2) Free chlorine alone at the
generally recommended level of 1 mg/liter (3) Free chlorine at 0.3
mg/liter combined with copper and silver ions at a ration of 400 ug/liter
of copper to 40 ug/liter of silver (4) Copper and silver ions alone at the
same ratio as above. An isolate of Staphylococcus sp was employed for
bacterial challenge testing since previous work had shown that
staphylococci are more resistant to disinfection than are coli form
bacteria. The experiment was continued for 12 weeks.
In the test of free chlorine alone, location proved to be critical. In the
outdoor setting subject to strong sunlight and high temperatures, no
residual chlorine could be detected 3 to 4 hours after optimization.
Indoor, where environmental factors were much less extreme, a residual
level of 0.1 to 0.3 mg/liter was found after 24 hours.
Bacterial counts were kept within drinking water standards (as recommended
for swimming pools) by either high levels of chlorine alone or by the
combination regimen of copper and silver ions with low levels of chlorine:
the difference in total bacterial numbers was not significant. Hen
challenged with Staphylococcus sp isolate, the combination of copper and
silver ions with low levels of chlorine achieved a 2.4 log 10 reduction in
bacterial numbers within 2 minutes, while the single-agent regimes (free
chlorine alone, or copper/silver alone) showed only 1.5 & 0.03 log 10
reductions respectively. Under Staphylococcus sp challenge, the combined
copper/silver and free chlorine had a faster log 10 reduction of microbial
numbers than did treatment with a high level of chlorine alone.
The addition of electrolytically generated copper/silver ions in the radio
tested (400 ug/liter copper to 40 ug/liter silver) allowed reduction in
the concentration of free chlorine to one third of the level customarily
recommended. The use of copper/silver may provide resisting protection in
swimming pools after chlorine has been rendered ineffective due to
contamination from swimmers and the natural environment.
warming, high energy prices and dwindling natural resources have put
“green” practices and technology in the forefront of public
discussion. Attention has focused on energy consumption, air and water
pollution, production of heat-trapping gases and other topics.
Where do point-of-use/point-of-entry (POU/POE) water treatment and bottled
water fit into this big picture?
Veteran POU/POE and bottled water dealers could say they’ve always been
“environmentalists” — providing people and businesses with clean
water that contributes to human health and well-being. At the same time,
with their knowledge of water contamination issues, many dealers and their
trade associations have been energetic advocates of water supply
But at the practical or technical level of conducting a water treatment or
bottled water business, what does it mean to adopt “green”practices?
Perhaps as importantly, how can water treatment for a sustainable
environment promote dealers’ business success?
Technology always helps
Dealers looking for “green” solutions for their customers won’t find
a shortage of products, systems and techniques from manufacturers and
distributors who tout their products as helping to reduce environmental
impacts, reduce energy consumption, etc. Many of the latest such POU/POE
or bottled water products do, in fact, represent technical innovations or
tweaks that do any or all of the following:
- Reduce energy consumption (as in water treatment
system components or appliances). One example of this might be digital
water system controls that minimize pump operations or water
consumption (which influences pump operation) to only that which is
necessary for proper treatment.
- Reduce or minimize chemical or raw materials
consumption in water treatment or bottled water production. Examples
of this might be ozonation, ionization or ultraviolet disinfection to
reduce dependency on chlorination, or the recent expansion of
- Reduce wastewater discharges that are a consequence of
POU/POE treatment. Minimizing brine discharge with demand-initiated
regeneration controls is one common example, but there might be other
techniques, such as sequestration and off-site destruction or
decontamination of toxic contaminants that could accumulate in a
system, such as arsenic.
- Reduce water consumption (see sidebar, Page 25). While
it’s a good idea generally to conserve water resources, the dealer
also can focus this as it applies to home and commercial treatment
systems and plumbing.
Trade associations and certifying bodies in the POU/POE and bottled water
industries aren’t standing still when it comes to “green” issues.
For instance, the Water Quality Association (WQA) this year will begin to
assist the US Environmental Protection Agency’s (EPA) WaterSense
water-efficiency program by helping EPA develop water-efficiency standards
for POU/POE products. WQA also has invited presenters at its WQA Aquatech
USA trade show in March 2008 to submit papers on “green” water
treatment, among other topics.
The federal government’s ENERGY STAR program now lists qualifying
energy-efficient products in at least three categories of interest to
dealers: water coolers, commercial ice makers, and geothermal heat pumps.
Through the NSF International and WQA Gold Seal systems, products are
certified to meet certain agreed-upon performance or materials standards
in water treatment. More “green” standards for POU/POE products are
bound to emerge from those same certifying organizations.
The US Green Building Council provides its voluntary Leadership in Energy
and Environmental Design (LEED) rating system for measuring the
environmental impact and efficiency of buildings. The water systems
component of that, however, is still in its infancy.
Only pale ‘green’?
Dealers must keep a careful eye out for products claiming to have certain
“green” qualities that either don’t meet some objective, scientific
criteria for those qualities or have been given that kind of label to
serve only a marketing function.
Some can stray into uncharted territory in that regard. For instance, a
pro-green Web site, sustainableBusiness.com, recently gave a top
“green” ranking to a company that the site says offers chemical-free
water treatment. The company’s specialty, it turns out, is magnetic
water conditioning, a highly controversial (and, some say, unproven) area.
Look for the less-conventional
Still, dealers shouldn’t automatically shun technologies simply because
they’re less conventional. They can still be genuinely “green” and
offer value to customers and more business for dealers.
A number of low-chemical or no-chemical descaling systems are now getting
a second look, for instance.
Solar-powered water systems for individual homes and businesses are
becoming more common, and solar has made considerable inroads into the
municipal treatment sector.
Even rainwater collection systems could become more common in the
developed world. Dealers can educate consumers about how collected
rainwater, presumably pristine but still containing organic and inorganic
debris, still must be treated.
In any case, “green” water treatment appears to hold promise for the
Earth, and for dealers’ bottom lines.