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Sump Pump discharge line size?

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  • Sump Pump discharge line size?

    I have three questions regarding sump pump discharge line plumbing. I live with a high water table and need to maximize my existing pumps ability to remove the water while I consider more expensive alternatives to controling the water.

    I currently have a Rigid 1 HP primary with a watchdog backup. Both are plumbed with 1-1/2", but "Y" together into an existing 1-1/2" line that exists the house.

    1. The standard discharge line is 1-1/2"; is there any advantage in using 2", or would the pumps performance suffer?

    2. It seems to me that check-valves dramatically affect the size of the discharge line. A 1-1/2" line is restricted down to about 1" at the check-valve. Are there true low-restriction check-valves available?

    3. If "Y'ing" the primary and backup pumps together (both with 1-1/2' discharge lines) before existing my basement, should I convert to 2" after the "Y", or simply run two discharge lines outside to a dedicated 3" or 4" main discharge line? NOTe: The backup pump does pump at the same time when the primary pump can't keep up.

    Thank you for your input...Scott
    Last edited by sandrew; 03-04-2009, 10:13 AM.

  • #2
    Re: Sump Pump discharge line size?

    I grew up in the nw suburbs of Chicago we had a basement that would get more water than we wanted
    If you went 2" from the pumps you can use a 2" check valve, with less resistance it should flow at the pumps maximum capacity
    then 1 2" line away from the house


    • #3
      Re: Sump Pump discharge line size?

      Oversizing the horizontal would reduce friction loss, thus increasing capacity/performance. But I wouldn't oversize the vertical--that would be more head pressure, thus decreasing performance. But I stand to be corrected.