RO system pre-fill & sanitizing

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by jag_man653, Nov 2, 2009.

  1. jag_man653

    jag_man653 New Member

    Messages:
    26
    The instructions for installation of my new Watts residential RO system give instructions for pre-filling and sanitizating the storage tank. It says to connect the tank to the "feed water line." If I understand correctly, this will put mains pressure on the tank, whereas in the normal hookup the pressure seen by the tank is after going through 4 stages of filtration.

    Will the tank take mains pressure, perhaps 50-60 psi?

    Is this procedure recommended and necessary?

    Just want to be sure I don't ruin something.

    TIA

    Ed
  2. Gary Slusser

    Gary Slusser That's all folks!

    Yeah it takes time and effort but that's what they obviously want done.
  3. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

    Messages:
    1,328
    Location:
    Columbus, OH
    Yes. Do it. Last thing you want is bacteria growing in your non-chlorinated membrane.
  4. jag_man653

    jag_man653 New Member

    Messages:
    26
    Gary & Lakee,

    Thanks. I'll do it.

    Ed
  5. BeanAnimal

    BeanAnimal New Member

    Messages:
    21
    The pressure drop across the filters is only measurable during operation. During idle periods, the pressure in all portions of the system, including that in the product side of the storage tank is the SAME as your static line pressure (in your case 50-60 P.S.I.)

    As Lakee indicated, it is very imporant to keep things as sterile as possible, the product water has no ability to fight bacteria. When you change filters, it is important to sanitize your housings and associated parts. Clean the membrane housing, but never expose the membrane to chlorine.
  6. jag_man653

    jag_man653 New Member

    Messages:
    26
    Thanks.

    The Watts sanitization instructions says to use bleach to sanitize the membrane housing as well as other housings. Wouldn't that pose a risk of contaminating the membrane?

    Ed
  7. BeanAnimal

    BeanAnimal New Member

    Messages:
    21
    Wash it and drain it well and you should be fine. If you are still concerned, let it dry for a few minites (chlorine evaporates).
  8. jag_man653

    jag_man653 New Member

    Messages:
    26
    Thanks again.

    Now that I read the Watts Installation instructions more carefully I see that it omits most of the sanitization steps listed under Maintenance. The only mention of sanitization in the Installation instruction section is a sort of causul mention of it where it describes pre-filling of the tank, and even there it does not include it in the step-by-step. One has to refer to the Maintenance section just to see how much bleach to add to the feed tube. So, other than (perhaps) sanitizing the tank, the Installation instructions just say to hook it up and allow the system to fill the tank a couple times, flushing the "sanitizing solution" down the drain after each charge.

    So, I now believe that there must be a sanitization chemical in one or more of the cartridges, making it unnecessary to run bleach through the pre-filter and membrane housings prior to installation of the cartridges. I'm thinking about putting bleach in the tank feed tube during pre-fill, draining it, and proceeding with hook-up.

    Am I reading things correctly here?

    Ed
  9. Gary Slusser

    Gary Slusser That's all folks!

    Chlorine damages (read ruins) membranes.

    Just install the thing and allow it to fill the tank and then you empty the tank and refill it like they tell you to and don't do anything they don't tell you to do and you and your RO will be just fine.
  10. BeanAnimal

    BeanAnimal New Member

    Messages:
    21
    The membrane ships wet with a presrvative in it. The filters, dry. The tank has a rubber bladdar in it that may have manufacturing oils (release agents, etc) on it, as may the housings.

    Standard practice is to set the unit up and run the output into the drain for 10 or so minutes to clear the membrane. Fill the RO resevoir once with clean product water and drain it... your good to go. The sanitizing steps are more important when changing filters and/or the membrane.
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