should we drink the water?

Hi Folks,

As one of the resident microbiologists on the list I would like to add a few comments on bacterial 
contaimination.  For the first thing...we want to think of what is going into the RO unit.  We are 
usually not taking water from an open sewer and putting it into are RO unit.  We are taking water 
that is, in the most part, rather clean stuff that has been ozonized (in Europe) and chlorinated 
(in the US) and a great deal of the microorganisms in the water have been killed.  The big question 
is what is left in the water.  If you were to take water from the tap and put it on growth medium 
on a petri dish you can get colonies to grow.  The fact of the matter is that these organisms are 
bugs that don't make you sick.  There are really very few microorganisms that make you sick, and in 
the cases where people get sick they are often immune compromised (by HIV, age, preexisting medical 
condition) and are unable to fight infections.  For the most part we have been exposed to these 
same microbes our entire lives and we never get sick from them.  If you are really worried about 
drinking RO water, then boil it first, or run your water through a UV sterilizer before it goes 
into your collection basin.

I think water directly from the RO unit is safe.  The water from your collection basin is another 
matter.  Many question come to mind.  What was the collection basin used for prior to its becoming 
a collection basin?  Is the water stored open or closed?  When the container is filling is the lid 
on or off and if off where is the lid being stored?  Someone  (i think Craig) mentioned 
contaimination with Legionella bacteria.  This can occur in an open container.  If you were to 
check your water supply for Legionella you would find that ALL water supplies contain some 
Legionella sp.(causes Legionaire's disease), Psuedomonas (which causes gangrene, upset tummy),E. 
coli (which can cause diarhea and upset tummy) and a plethora of other bugs.  The fact of the 
matter is that only a miniscule subpopulation of bacteria in a natural environment are able to 
cause and sickness in animals and it is incredibly rare for problems to occur.  If this wasn;t the 
case then every place with air conditioners would have people falling over dead from legionaire's 

I drink my RO water.  I collect the water in a carbouy (a large PVD container with a spigot at the 
bottom).  I wash the carbouy with diluted bleach (10% chlorox solution) every once in a while and 
thoroughly rinse the container with tap water after the sterilization (i want to get rid of 
bacteria that might have built up over time...i don;t care if I might be adding a few more).  I add 
the water and i enjoy it much more than the baking soda flavor water that we have here in central 
texas.  i am still alive.

My 2c on the topic.


    jdavis at bio_tamu.edu
    jmd9261 at tam2000_tamu.edu