Abandoned line in wall; stagnant water a concern?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by speede541, Jun 21, 2013.

  1. speede541

    speede541 Member

    Messages:
    124
    Location:
    San Francisco Bay area
    I'm installing a bunch of copper that serves current fixtures, but also runs to locations of planned fixtures.

    Nearly every current fixture will disappear, and the abandoned stub that I'll cap will stay connected to the branch line continuing on to the future fixture location.

    Under this scenario, is there any concern with stagnant water entering the branch? The abandoned lengths will be limited to a foot or two at most, and all connect vertically above the in-service branch. This is all bathroom and laundry service, for what it's worth.
  2. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,395
    Location:
    Yakima WA
    I can't see how that water will be stagnant if it is still connected to the water supply. Does water become stagnant in a water line that is not used often? I don't think so. In the interest of neatness, I might try to cut the stub as short as possible, but not to prevent stagnation.
  3. craigpump

    craigpump Well-Known Member

    Messages:
    1,076
    Location:
    ct
    I would remove the old pipes. Bacteria from stagnant water or from working on the plumbing can "hide" at the end of those runs and could potentially contaminate your water supply. Treating/killing the bacteria will be tough because the water won't flow back into those stubs.
  4. kreemoweet

    kreemoweet Member

    Messages:
    377
    Location:
    Seattle. WA
    What a ridiculous statement. It is the RARE water supply system that doesn't have numerous "dead ends" in both the supply pipes and fixtures, and there is no
    danger from "stagnant" water (whatever that's supposed to mean) or from nonexistant "bacteria". There is little to nothing in modern water supply systems to support
    the growth of microorganisms, and of course the water has usually been treated with chlorine and other disinfectants. If you're piping skunk water into your house from
    some nasty pond in the back woodlot, then you might have something to worry about.
  5. Terry

    Terry Administrator Staff Member

    Messages:
    15,413
    Location:
    Bothell, Washington
    I don't see any problems with that.
  6. craigpump

    craigpump Well-Known Member

    Messages:
    1,076
    Location:
    ct
    @ Kreme, I see it all the time when a well is chlorinated and someone doesn't get chlorine through the entire system. That one little obscure spigot or delivery to a humidifier can harbour coliform bacteria that can/will reproduce and re contaminate a water supply.
  7. speede541

    speede541 Member

    Messages:
    124
    Location:
    San Francisco Bay area
    stag·nant: Adjective
    (of a body of water or the atmosphere of a confined space) Having no current or flow and often having an unpleasant smell as a consequence.
    Showing no activity; dull and sluggish: "a stagnant economy".

    I've seen the insides of old pipes and they're far from pristine. Not saying it's bacterial infestations, but I don't want to drink it. Hence my question.

    I get what your saying about "dead ends" existing in a system, but I'm betting that water doesn't see any movement, i.e. stagnant. I'll roll with it, though.


    Great, thanks.
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