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Thread: 1/2" from street adequate?

  1. #1

    Default 1/2" from street adequate?

    Hey there.

    I'm in the middle of a bathroom remodel on a small 1 bed, 1 bath house. The supply line coming in from the street is 1/2" galvanized, though I've cut out all the supply plumbing for the bath and will replace w/ copper. Everything I've read suggests 3/4" minimum trunks w/ a max of two fixtures per 1/2" trunk. Obviously, I can't do this w/ a 1/2" trunk. Assuming I'm not going to take the time to run a new line from the street, I have a couple of questions:

    1. Will it help w/ pressure/flow if I run just one fixture per branch, even though it will be 1/2" everywhere?

    2. The bathroom is right where the water comes in from the street, and it was previously plumbed w/ the all the bathroom fixtures branching off (cold only, obviously) before exiting to the hot water heater and other fixtures. Should this be done differently now that I have the opportunity? I'd rather not replumb the rest of the house right now, but . . .

    3. Would it make a difference if I converted the 1/2" to 3/4" where it enters the house, or is all/most the pressure/flow already lost?

    FYI, all the fixtures in the house are:

    BATH: toilet, sink, bathtub w/ showerhead
    KITCHEN: sink, dishwasher
    OTHER: two hosebibs, washer

    I don't have much info on how well things worked b/f, as I just bought the house and ripped it all out w/o checking to much (Yes, I know I am dumb.). Any help would be appreciated. Thanks.

    -Greg
    Last edited by gregoryc; 10-05-2008 at 06:34 AM.

  2. #2
    Plumber jimbo's Avatar
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    Default

    Today, 1/2" would not be considered acceptable service in ANY house. Even a small house like yours would have a 3/4" service. Anyplace you can increase the pipe size will MINIMIZE your pressure LOSS, but you cannot regain the pressure drop that will occur in that 1/2" galv. pipe, especially considering the condition it must be in.

  3. #3
    Plumber Cass's Avatar
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    I would run 1" from the street to your home. 3/4 would probably be fine but for the small extra cost difference of the pipe why not go with 1"...every thing will flow better.

  4. #4
    Moderator & Master Plumber hj's Avatar
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    Default pipe

    I cannot visualize ANY competent plumber using a 1/2" galvanized line to feed ANY building. Once it started corroding, and it would only take a few years, its capacity would plummet from the already marginal amount it started with.

  5. #5

    Default

    Ok, that's what I was afraid of.

    Assuming I have to leave it for now though, what about the answers to 1, 2, and 3, above?

    Thanks again.

    -Greg

  6. #6
    Moderator & Master Plumber hj's Avatar
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    Default flow

    1. No.
    3. Very little if any benefit.
    2. Separating the flows as soon as possible will give the greatest benefit, although in your situation you may not be able to detect any difference.

  7. #7
    One who lurks Basement_Lurker's Avatar
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    This is a small house, and basically if you are going to do any work to it (which you obviously have already started before thinking about it), you really need to do a full repipe on it. There is no point to spending the $$$ to put in copper when you have a crappy choked up 1/2" galvanized line coming in from the street.

    As far as your plan to do separate branches to each fixture, it's a waste since this is only a 1 bath and 1 kitchen home. There isn't going to be much competition for simultaneous water use. As far as flow to each fixture, you should think of water demand in a branch and trunk piping system as first come first served.
    Broken promises don't upset me. I just think, why did they believe me? -Jack Handy


    www.blackbirdkitchenandbath.com

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