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RO/DI Water

>> The warning came from a process engineer in an integrated circuit
>> processing facility that used DI water to clean wafers. He remarked
>> that since DI water is so pure, it has no mechanisms to prevent
>> bacterial growth and, in essence, makes a nice breeding ground for
>> some very nasty germs.  People in the IC facility were warned about
>> drinking DI water for this reason.
>>
>> George
>
> Hi, I don't use either, but the same thing goes for RO water.  It 
> shouldn't be left in a holding tank very long.  In RO water there is
> no chlorine present that would help stop bacteria from forming.  I 
> think many people overlook this.  Here is a post.

I just ordered a new 150g HDPE reservoir for my RO/DI system so that I
could provide a cleaner enviroment for the water.  For one, this new tank
has a nicely sealed manhole-type cover that provides a better seal than my
current 100g rubbermaid tub with a sheet of countertop material over it.  I
plan to use a UV sterilizing unit that I will circulate the water through
on a regular basis to keep bugs from building up.  A local pet shop
installed a fairly sophisticated RO system that included UV and when asked
the owned claimed it did indeed prevent any bacterial growth in the water. 
So I'm building a similar less fancy version. Spectrapure seems pretty
confident in my new setup and they're supplying me with a little $50 vacuum
relief valve with a special air filter to keep bacteria from entering as
water is pumped out.  They still recommend occasional cleaning but claim it
will be required much less often.  Granted this is a little more than some
would want to do, but I hate cleaning the darned thing and I wanted
something in which I could see the water level.

My current tub always has a nice film on the sides.  I have a powerhead
installed to keep the water from stagnating.  Even though it is covered I
can't keep it sealed well enough to prevent the film from returning. 
Whatever it is that's growing in there doesn't seem to bother the tank
inhabitants.  We don't drink this water either.

I liked the H2O2 idea.  Our Spa uses H2O2 as part of the treatment system
that we use.  For the chemists; how long does H2O2 remain in water before
it simply becomes water and O2?  Or does it even do that?  It sounds safer
and less toxic than Chlorine.

Mike