How Can Water Distribution Systems Be Kept Secure?

[Steve Schear]

[Reformatted for legibility.  When posting tables, use spaces, not tabs,
keep total width <= 73 characters, and compose in a monospaced font,
unless specifying field delimiters.  KMSelf]

At 04:30 PM 10/8/2001 -0700, mmotyka at lsil.com wrote:
>UV is actually a very good disinfectant. It works by damaging the
>DNA/RNA of bacteria and virii. There is evidence of some viruses being
>re-activated by sunlight. UV coupled with a primary disinfectant like Cl
>makes a pretty safe system. The 4ft GE Quartz UV bulbs are powerful. The
>water should be clear - turbid water attentuates the UV too much.
>
>In very poor places where many children die of dehydration because of
>contaminated water and where there is little or no money for water
>systems, aid workers have taught the kids to put water into clear
>plastic drink bottles ( the kind our landfills are clogged with ) and
>leave it in the sun. It works quite well.
>
>How are RO systems at removing microorganisms?

[From some consumer spec comparisons to a RO unit I use]

Types Of Drinking Water Appliances & Pollutants Removed

Pollutant      Sediment Activated Reverse Distil-  De-Ion-  UV
                 Filter   Carbon  Osmosis  ation   ization
  Sodium           No        No      Yes     Yes     Yes     No
  Arsenic          No        No      Yes     Yes     Yes     No
  Lead             No        No      Yes     Yes     Yes     No
  Cadmium          No        No      Yes     Yes     Yes     No
  Cysts            No       Some     Yes     Yes     No      Yes
    (Crypotosporidium)
  Sulfates         No        No      Yes     Yes     Yes     No
  Calcium          No        No      Yes     Yes     Yes     No
  (Hardness)
  Magnesium        No        No      Yes     Yes     Yes     No
    (Hardness)
  Phosphates       No        No      Yes     Yes     Yes     No
  Chlorides        No        No      Yes     Yes     Yes     No
  Florides         No        No      Yes     Yes     Yes     No
  Alkalinity       No        No      Yes     Yes     Yes     No
  Fecal Bacteria   No        Most    Yes     Yes     No      Yes
  Viruses          No        No      Yes     Yes     No      Yes
  Organics         Yes       Yes     Yes     Yes     No      No
  Trialomethanes   No        Yes     Yes     No      Yes     No
  Trichloroethlene No        Yes     Yes     No      Yes     No
  Ph Factor        No        No      Neutr  Neutrl  Neutr    No
  Radioactive      No        No      Yes     No      No      No
     Contaminates
  Chlorine         No        Yes     Yes     Most    No      No
  Pesticides       No        Yes     Yes     Yes     No      No
  Sediment         Yes       Most    Yes     Yes     Yes     No
  Unpleasant       No        Yes     Yes     No      Yes     No
    Taste/Odor