re: RO and DI water

---------- Forwarded message ----------
Date: Tue, 21 Jan 97 18:20:41 -0800
From: John <jlob at wpa_net>
Organization: WPA
To: Aquatic-Plants at actwin_com
Subject: Re:  Ro and  DI Water

>George Booth wrote

> 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.  

>The main problem with RO, as anyone who sells RO systems for DRINKING>WATER (POU) knows, is bacterial contamination. Chlorinated wa=
ter is not>bacteria-free.  RO systems are notoroius for growing HEAVY loads of>bacteria, if not properly cared for.  RO systems shou=
ld be flushed with>hydrogen peroxide or dilute bleach every 6 months or so.  I "peroxide" my>RO every time I change the carbon and p=
refilters.  I have to remove the>membrane and filter carts, add my H202, and fill the system.  I use a>?pressure tank to hold the wa=
ter for drinking. I allow this tank to fill >up with "H2O2 water", then empty the tank, replace the membrane and >filter units.  Pai=
n in the butt-but necessary for safe drinking water.

Keep in mind that some membranes need chlorine because they are 
susceptible to bateria= CTA membranes.  TFC membrances are more 
resistant to bacteria, but can't have chlorine run through them or it will 
destroy them.  For them the source water is first run through a carbon 
prefilter to eliminate the chlorine.