Loading ...
Sorry, an error occurred while loading the content.
 

Jug Water Filter Cartridges - Safety & Effectiveness

Expand Messages
  • Michael Meredith
    Household jug water filters have become very popular - usually to remove the taste of chlorine and/or potential domestic water supply contaminants such as:
    Message 1 of 1 , Apr 15, 2006
      Household jug water filters have become very popular - usually to
      remove the taste of chlorine and/or potential domestic water supply
      contaminants such as: lead, chlorine, fluoride, trihalomethanes
      (water chlorination by-products), iron, manganese. Filters are often
      preferred, especially indoors, to bottled water because of lower
      cost and greater convenience.

      Sometimes there is hope that a filter will also remove or reduce the
      risk of waterborne diseases like: Cryptosporidium, Giardia, E.coli,
      Salmonella.

      I have recently investigated how safe and effective a jug filter is
      likely to be. My primary interest was in the question of silver
      toxicity - especially when people self-medicate with colloidal
      silver. Actually there does not seem to be any reason for concern
      about silver toxic effects from these common household filtration
      cartridges, but I did turn up a number of other health risks (and
      potential health benefits) from filtered water...

      What's in a Jug ("Pitcher" in U.S. English) Filter?
      --------------------------------------------------
      Jug filters normally comprise granular activated carbon (GAC) and a
      weak base ion exchange resin impregnated with silver ions. The ion
      exchange resin serves to replace the calcium and magnesium ions in
      the water with hydrogen ions, thereby softening the water and
      reducing pH (i.e. making the water slightly more acidic). GAC
      removes chlorine and SOME organic material from the water. The
      silver ions act as a (bacteriostatic) biocide to reduce bacterial
      accumulation in the filter cartridge. "Bacteriostatic" means that
      the silver tends to control numbers of bacteria, rather than totally
      eliminate them. However, the risk of infection by food poisoning
      bacteria is often dose-related i.e. reducing numbers can have a
      significant protective effect in some cases.

      Effectiveness of Jug Drinking Water Filters
      -------------------------------------------
      [edited extract from http://www.homeenv.com/art_wtr_filt.htm%5d

      Chlorine is one of the easiest contaminants for carbon to remove -
      there is adequate carbon in a typical cartridge for NSF Class I
      chlorine removal. Filter cartridges are much less efficient for
      removing other contaminants such as trihalomethanes, MtBE, MX, trace
      pesticides/herbicides, and many other VOC's because these potential
      contaminants require more carbon "contact" time.

      Carbon filters will not usually remove all dissolved inorganic
      contaminants (dissolved solids e.g. heavy metals). Some carbon
      filters will remove lead and some copper but other dissolved
      inorganics will pass through unobstructed: dissolved minerals/salts,
      antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium,
      copper, fluoride, mercury, nickel, nitrates/nitrites, selenium,
      sulfate, thallium, and certain radionuclides. With the exception of
      lead and fluoride, removing these contaminants requires either a
      reverse osmosis water filter system (RO system) or a water
      distiller. Lead can be removed through specialty carbon filters and
      there is a type of activated alumina cartridge that can be used for
      fluoride removal.

      Safety Concerns and Precautions for Risk-free Use
      -------------------------------------------------
      [edited extract from
      http://www.unitedutilities.com/resources/files/40_WaterHealth_Issue_34.pdf%5d

      An extensive UK study came up with the following conclusions about
      jug-filtered water:

      * A significant reduction in pH in filtered water.

      * Bacterial levels were slightly higher in the filtered water
      compared to the feed water, but overall there was no evidence that
      jug water filters had an adverse effect on microbial water quality.

      * If the filter was used beyond the designated lifetime (normally
      28 days) there was an increase in bacterial numbers in the filtrate.

      * A difference in taste and odour between filtered and unfiltered
      water, this was due to the removal of chlorine by the filter.

      * Bacterial numbers were high in the first litre filtered after a
      period of non use. (Manufacturers normally recommend that the first
      two litres of water should be discarded).

      * Higher concentrations of silver ions in the filtrate than the
      feed; the levels declined as the water filter aged. There is limited
      toxicity data on the presence of silver in drinking water and
      currently no regulatory standard.

      * Elevated levels of nickel in the filtered water after boiling.

      * Filters were spiked with high concentrations of the foodborne
      pathogens: Salmonella and Escherichia coli to simulate cross-
      contamination of the filter from general activities in the kitchen.
      These organisms were only present in the first litre filtered after
      their introduction. This suggests that the silver ions do act as an
      effective biocide.

      World Health Organization Report
      --------------------------------
      [edited extract from
      http://www.who.int/water_sanitation_health/dwq/WSH02.07.pdf%5d

      Charcoal and activated carbon have been used extensively as
      adsorbents for water treatment in the developed and developing
      world. Charcoal or activated carbon will adsorb microbes, including
      pathogens, from water, but dissolved organic matter in the water
      rapidly takes up adsorption sites and the carbon rapidly develops
      a "biofilm" coating. Therefore, carbon is not likely to appreciably
      reduce pathogenic enteric microbes in water over an extended period
      of time. If anything, carbon particles are prone to shedding
      microbes into the product water, thereby reducing the microbial
      quality.

      In many point-of-use devices the carbon is impregnated or commingled
      with silver that serves as a bacteriostatic agent to reduce
      microbial colonization and control microbial proliferation in the
      product water. Fecal indicator bacteria, such as total and fecal
      coliforms, and opportunistic bacterial pathogens, such as Aeromonas
      species are capable of colonizing carbon particles and appearing in
      product water. For these reasons, activated carbon is not
      recommended as a treatment method to reduce pathogenic microbes in
      drinking water. Additional treatment, such as chemical disinfection,
      often is needed to reduce microbe levels in carbon-treated water.
      Mixed media containing carbon along with chemical agents effective
      in microbial retention have been developed and evaluated. For
      example, carbon filters containing aluminum or iron precipitates
      have been described, and these filters have achieved appreciable
      microbial reduction in tests.

      Granular activated carbon filter media prepared with chemical agents
      which are more effective in retaining microbes may eventually become
      more widely available for point-of-use treatment of household water.
      However, the conventional charcoal and activated carbon media
      currently available for water treatment are not recommended for use
      at the household level to reduce microbial contaminants. Only
      charcoal or activated carbon media that been combined with other
      materials to improve microbial reductions should be considered for
      household treatment of collected and stores water and then only if
      there are performance data or certifications to verify effective
      microbial reductions.

      Limitations of Silver in Filter Cartridges
      ------------------------------------------
      [edited extract from
      http://www.who.int/water_sanitation_health/dwq/WSH02.07.pdf%5d
      Silver is used as a bacteriostatic agent for point-of-use or
      household water treatment by storing water in vessels composed of
      silver or passing water through porous or granular filter media
      impregnated with silver. However, the extent to which silver alone
      inactivates microbes in water is limited, bacteria may develop
      silver resistance and many microbes, such as viruses, protozoan
      cysts and oocysts and bacterial spores, are not inactivated at
      silver concentrations employed for point-of-use drinking water
      treatment.

      Author: Michael Meredith http://www.lovehealth.co.uk
      [This article may be distributed freely with the attribution that it
      is copied from "Cambridge Healing - Holistic Lifestyle Group":
      http://health.groups.yahoo.com/group/cheal/%5d
    Your message has been successfully submitted and would be delivered to recipients shortly.