Proper pipe size for shower valve on well water system

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by timsean, Mar 9, 2010.

  1. timsean

    timsean New Member

    Mar 9, 2010
    Chicago, IL
    Long time reader, but my first post.

    I am redoing my bathroom (45 years old), and will be putting in a new shower valve. The water is from a well. Since it's well water, the pressure and flow rate are lower than city water systems. My question is this: when replacing the shower valve, would a 3/4 valve be better? Would the increased flow rate feel provide a better shower? Or would the larger diameter mean a decrease in water pressure at the shower head? As it is now, a restricted flow shower head (the only kind they sell now) provides too little flow (we use an old shower head).

    The bath is right over a basement, so the main 3/4 lines are accessible for plumbing changes.

    Anyway, I am getting conflicting advice from 2 different plumbers, so I am confused. Any advice would be greatly appreciated.

    Thanks in advance!

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    A bigger line would only help if the current line was being asked to provide more water than it normally could. For most installations, a 1/2" valve will be fine. With one showerhead, it won't make a difference. if you had many, a larger valve would be useful. You may want to switch or adjust the pressure switch so you have higher pressure. If the pipes in the house have galvanized pipe, those could be corroded so they are the size of a pencil inside, and you may have good pressure, but lousy flow to your valve. What is the pressure switch set to?
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  4. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    Increasing the size will only increase the volume, IF your flow requirements are more than the smaller size would handle adequately. In your case that is not a factor, so the larger lines would not provide more volume OR pressure.


    Last edited by a moderator: May 22, 2016
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