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Drinking water information and resources, contaminants, health effects, treatment methods

Solid Block Activated Carbon Filtration
vs.
Reverse Osmosis or Distillation

It is important to understand the difference between Solid Block Activated Carbon (SBAC) Filtration and Reverse Osmosis or Distillation.  Occasionally people are disappointed with their water quality after installing a high-end SBAC filtration system and discovering that their filtered water still has an undesirable taste or odor. 

      If your untreated water has no unpleasant smells or tastes besides chlorine, an activated carbon filter will most likely provide excellent tasting and smelling water.  However, if your untreated tap water has a metallic, bitter or salty taste, activated carbon filtration will probably NOT be sufficient.  Other smells &/or tastes may or may not be reduced by activated carbon it depends on what the specific contaminants are.

      Taste and odor problems do not necessarily have anything to do with the safety of your drinking water many harmful contaminants have no taste or odor and many that cause unpleasant tastes and odors are not particularly harmful.  However, contaminants that cause taste and odor problems will make your water less pleasant to drink, and if you invest in a water treatment system, you expect to be able to drink water without disagreeable tastes or odors.  So, it is important to understand the strengths and limitations of activated carbon filtration.

      Activated carbon filters excel at reducing taste and odor problems caused by chlorine (the better models also reduce chloramines), and a wide variety of organic chemicals.  Taste and odor problems in municipal water from most cities in the U.S. and Canada can be effectively treated by a high quality SBAC filtration system because high levels of salts &/or metal ions are not usually a problem. 

      If, however, the taste or odor of your water is caused by salts (chloride or nitrates) or metal ions like iron, manganese, selenium, barium, cadmium, copper, etc. there are no activated carbon filters (SBAC or granular) that will effectively remove those contaminants and eliminate those tastes/odors.  In these situations there are several options:

o   If you have really poor tasting/smelling drinking water from a municipal water provider, it is important to understand what is causing the problems so you can order the most effective treatment option and not be disappointed by a system that fails to correct the problem.  To discover what contaminants are in your municipal water that cause the taste/odor problems you experience, you can read the annual water quality report from your water company or call your water provider and ask.  Some information about taste and odor problems can be found here.

o   If you discover that the contaminants that cause your taste/odor problems can't be removed by a high quality activated carbon filtration system, and they only affect your drinking water, the most effective treatment options would be a Point of Use distillation or reverse osmosis system.  A few municipal drinking water facilities may meet EPA requirements for safety, but still allow enough salts and metal ions to cause taste and odor problems.

o   If you have done some research and are still not sure whether a high-end SBAC filtration system by itself will significantly reduce the contaminants causing your taste and odor problems, you can experiment with a cheap activated carbon pitcher filter.  While I do not recommend them as long term treatment solutions because of their relative ineffectiveness, low treatment volumes and high long-term expenses for replacement cartridges, they might provide some useful information. 

  1. Fill the pitcher filter with your tap water and allow it to go through the filter.
  2. After the water has been filtered, pour it back into the top of the pitcher and let it percolate through the filter again  (to increase effectiveness) - you could even run the water through the filter a third time.  The activated carbon in the pitcher filter will reduce a similar group of contaminants as a high-end SBAC filter cartridge and also will not reduce the salts or metal ions.  So, any remaining contaminants in the pitcher-filtered water that cause taste and odor problems should be similar to those remaining in the high-end SBAC filtered water.
  3. In order that your expectations do not get in the way of your observations we will blind the test. This is also a good method to determine which wine or beer brand really tastes better and it can solve important family disputes like, "does day-old coffee taste worse than freshly made coffee?"
    1. For the blinded water comparison you will need to find a friend or family member who will assist in the experiment but not participate in the sampling.
    2. The assistant will draw as many glasses or cups of unfiltered water and filtered water as there will be people sampling the water while those participating in the experiment are out of the room - and not watching. 
    3. The assistant will set the water glasses on a table or counter, one filtered and one unfiltered glass of water for each person participating in the experiment.  The assistant will record (or diagram) which of the glasses contains filtered water and which contains unfiltered water.  It does not matter whether the order of filtered/unfiltered water is the same or different for each experiment participant, only that the assistant has a good record.  The record of which glass is which will not be shared with the experiment participants until step 7.
    4. The glasses will need to stand until all water reaches about the same temperature.
    5. The assistant will withdraw from the room, remove all documentation about the contents of the glasses, and notify the experiment participants that they can go in and sample the water.  The assistant will provide no hints about the placement of the water, and it is best that the assistant remain out of the room to avoid compromising the experiment by tossing out inadvertent comments.
    6. The participants will enter the 'experimental chamber' with note paper and pens, take their stations in front of the water glasses, carefully sample the water in each glass without commenting to other participants, take notes about the taste and odor of each sample, and not change the arrangement of their glasses.
    7. Once everyone has sampled water to their satisfaction and recorded their observations, the assistant will re-enter the room and unblind (identify) the contents of each glass.
    8. It should be fairly obvious whether the activated carbon has made a significant, noticeable difference in the taste and odor of your tap water, and you can use the results to determine whether a high-end SBAC filtration system will be an optimal solution for you or whether reverse osmosis or distillation would be the better option.
    9. Good luck!
       

o   If your taste/odor problems affect all home-use water (drinking, bathing, washing, etc.) a whole house treatment solution might be required.  Normally these extreme methods are only needed for private well water, not municipal water. 
 

o   As I have mentioned elsewhere, private well, spring or surface water sources can have a wide range of potential contaminants and may require extensive testing, specialized whole house treatment methods, and constant monitoring.