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Become Informed
about the benefits, limitations, and costs of the various POU water treatment methods.

Effectiveness Of Water Treatment Method
 Contaminant
     harmful contaminant
   * harmful at high levels    
 Inorganics
  Disinfection Chemicals
     chlorine Ev Ev Ev - Er E - - E Add - - - Eb Eb
     chloramine Edv Edv - - Er E - - S Add - - - Eb Eb
  Positive Ions
     cadmium - - - - Er E - - Con - E - - Eb Eb
     calcium - - - - Er E - - Con - E - - Eb Eb
     copper *+ - - - - Er E - - Con - S - - Eb Eb
     iron - - Es - El E - Es Con

Es

 El - - Eb Eb
     lead + Edv Edv Es - Er E - - Con - S - - Eb Eb
     mercury Edv Edv - - Er E - - Con - S - - Eb Eb
     manganese - - - - El E - Es Con Es El - - Eb Eb
     sodium * - - - - Er E - - Con - Ads - - Eb Eb
  Negative Ions
     arsenic - - - - Er E - - Con - - E E Eb Eb
     carbonate - - - - Er E - - Con - - E - Eb Eb
     chloride - - - - Er E - - Con - - E - Eb Eb
     fluoride * - - - - Er E - - Con - - - E Eb Eb
     nitrite & nitrate = - - - - Er E - - Con - - E - Eb Eb
     perchlorate - - - - Er E - - Con - - E - Eb Eb
     sulfate* - - - - Er E - - Con - - E - Eb Eb
  Inorganic Particulates
     asbestos fibers Ep - - Ep

E

 E - - Con - - - - Eb Eb
     sand, silt Ep Ep Ep Ep Rp E - - Con - - - - Eb Eb
  Radionuclides
     radon Edv Edv - - - - - -  E -  -  -  - Eb Eb
     radium - - - - Er E - - Con - E  -  - Eb Eb
     uranium - - - - Er E E - Con - E  -  - Eb Eb
  Odor Causing Inorganics
     hydrogen sulfide * Elv Elv Es -  -  - -  Es E Es -  S - Eb Eb
 Organic Compounds
  Disinfection Byproducts
     trihalomethanes Edv Edv - - S - -

Etc

 E Cr - - - Eb Eb
     haloacetic acids Edv Edv - - S - - Etc E Cr - - - Eb Eb
  Pesticides = Edv Edv - - Er E - Etc Con - - - - Eb Eb
  Solvents Edv Edv - - Er E - Etc Con - - - - Eb Eb
  ^ Pharmaceuticals,
   Hormones, Home &
   Personal Care Products 		Edv Edv - -  Er  E - Etc Con - - - - Eb Eb
  ^ Other Organics Edv Edv - -  Er E - Etc Con - - - - Eb Eb
      MTBE & EDB   Edv Edv - -  Er E - Etc Con - - - - Eb Eb
      PCBs Edv Edv - -  Er E - Etc Con - - - - Eb Eb
  ^ Organic Particulates Ep Ep - -  Er E - Etc Con - - - - Eb Eb
  ^ Odor/Color Causing
      Organics 		Edv Edv - -  Er E - Etc Con - -  S  - Eb Eb
  ^ Volatile Organic
      Chemicals (VOCs) 		Edv Edv - - - - - Etc E - - - - Eb Eb
 Harmful/Parasitic Microorganisms 
  Enteric  Viruses - - - - Ei E E E E E - - - Eb Eb
  Bacteria Svp - - Epi Ei E E E E E - - - Eb Eb
  Protozoans Edv - - Edv Ei E S E E S - - - Eb Eb
 Approximate price 
 per gallon		 $0.04
to
$0.10		 $0.01
to
$0.25		 $0.01
to
$0.06		 $0.01
to
$0.04		 $0.10
to
$0.20		 $0.25
to
$0.35		 L.T.
$0.01		 L.T.
$0.01		 L.T.
$0.01		 L.T.
$0.01		 L.T.
$0.01		 L.T.
$0.01		 $0.02
to
$0.04		 $0.25
to
$1.50		 $1.00
to
$6.00
 Contaminant
     harmful contaminant
   * harmful at high levels  

Key  Description
    - Not effective or not recommended for reducing the level of a contaminant.
   E Effective at reducing the contaminant level.
   Eb Effective - bottled water quality is entirely dependent on the quality of the company producing it.  At  minimum, it must meet quality requirements that are equivalent to those for tap water.
   Ed  Effectiveness at reducing the contaminant level depends on the manufacturer's specific design.  For GAC filters, one of the design considerations includes possible channeling/dumping.
   Edv Effectiveness at reducing the contaminant level depends on design & volume of the filter media.
   El Effective at reducing low levels of the contaminant.
   Elv Effective at reducing low levels of the contaminant.  Effectiveness depends on the volume of the filter media
   Ep Effectiveness at reducing the contaminant level depends on the pore size and type of media.  For GAC filters, large-loose carbon granules and possible channeling, make pore size determination difficult.
   Er Effectiveness at reducing the contaminant levels depends on the characteristics of the revere osmosis membranes, the specific contaminants in the water and their concentrations, and the water pressure.
   Ev Effectiveness at reducing the contaminant level depends on the volume of the filter media.  A filter with a larger volume of filter media will reduce contaminants better than smaller filters.
   Ei Effective if the RO or micro membranes are intact.  Any defect could allow microorganisms into the "filtered water" stream.  There is no way to know, though, if the membranes are completely intact.  Not recommended for use on biologically unsafe water.
   Epi Effective at protecting against bacterial contamination if the pore size is small enough (<0.5 micron and the filter media is intact.  Not recommended for use on biologically unsafe water.
   Etc Effective ozone treatment oxidizes many organic chemicals and transforms them into smaller molecules,  creating nontoxic or toxic byproducts depending, in part, on ozone exposure and the original organic compounds.  
   Es Treatment produces a sediment/deposit that might need to be filtered or backwashed.
   S Somewhat effective at reducing the contaminant level.
   Sdv Somewhat efectivene at reducing the contaminant level depends on design & volume of the filter media.For GAC filters, the possability of channeling & dumping can reduce effectiveness.
   Sv Somewhat effective.  The greater the volume, the better the contaminant reductions.
   Rp Contaminant is typically removed prior to entering the filter.
   Con Contaminant can be concentrated by the treatment method.
   Add Specific contaminant added to the water by the treatment method.
   Ads Most water softeners replace calcium and other cations with sodium.
   Cr Treatment method creates new contaminants in the water.
   + Lead is not frequently in water that leaves the municipal water treatment plant.  If the water is corrosive, minerals (frequently lead and copper) can leach out of a home's plumbing and fixtures.
   =  Nitrites, Nitrates, and Pesticides are not typically in municipal water.  These compounds are regulated by the EPA, and if the water company is in compliance the levels should be below the EPA's MCL.  There will probably always be some companies, however, that are out of compliance, particularly in heavily agricultural regions.  The water quality report should have information about whether these contaminants are a problem in your water.
    ^ There are many specific organic chemicals in each of these categories, many harmful, many not.  The Key simply indicates treatment methods that are listed in the literature as effective against representative compounds or stated as a treatment method of choice.  Check with the specific manufacturer (or certification organization) about specific contaminant removal.

*

 Cation exchange - Water softeners use cation exchange to replace positive calcium and magnesium ions with a different ion (usually sodium) that does not cause the problems of mineral deposits and other nuisances. 

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Copyright © 2005 Randy Johnson. All rights reserved.

Updated April 2015