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Avg. Sump Pump discharge rates???

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  • Avg. Sump Pump discharge rates???

    I've been having a string of issues with my Sump pump and I think I have been troubleshooting the symptoms and not addressing the root cause. Let me give you some history. First, about a month ago I noticed next to my deck water coming up next to one of the posts. My wife noticed it would come out of a hole whenever the sump would run (which it seems to do often, always has..) anyway I dug from where the sump discharge leaves the house and goes into the ground. I found 4" corrugated pipe heading right to the post. This is only about 3' away from the house at a 45 degree angle. (5'ish worth of pipe)

    SO I read up, dug a trench straight from the house, out 20'. The first 10' is 4" solid corrugated then a 10' section of perforated pipe with a sock about a foot of gravel. Then wrapped in in cloth. The top of this was under a bit over a foot of soil. And let me tell you my soil is some pretty dense clay.

    I hooked up the sump discharge again (had it redirected with a 25' temp hose) Watched it run for a few cycles, then went to sleep. By morning there was 2" of standing water on top at the end of the 20' and 1 at around the 15' length and just mud at the 10'.

    At this point I figured that maybe the clay was not pours enough or I didn't make it big enough. I talked to some local people (plumbing supply company and a place that specialized septic tanks etc) They both recommended a drywell.

    So, I dug all that out, and installed a 2' wide 3' deep drywell with between 6"-12" of gravel around it. It's top is 1' below grade and is 20' from the house.

    And so far in the last 5 hours since I hooked up the sump it has filled the drywell to 9" deep. Ignoring what ever water has drained into the surrounding gravel, and soil, a 2' wide cylinder at 9" deep is 4073 Cubic Inches or 17.63 Gallons of water...

    So all this history just to get to my question. Is 17.63 Gallons in 5 hours a crazy large amount?

    My house foot print isn't even 600 sq ft that is half basement and half gravel floor crawl space.

    - Should I worry about where this much water is coming from?
    - And what am I going to do to get rid of it?
    - Would running it to my property line be best? My back yard slopes to a common area of trees. I cannot by code run it to the street.
    - Bigger, deeper, wider Drywell?

  • #2
    Re: Avg. Sump Pump discharge rates???

    Most sump pumps I'm familiar with produce around 35 gpm at zero head. As you push the water up higher, down goes the flow. I would say average head is 8' from the basement floor to ground level, so I would look for around 20 to 25 gpm at 8'.


    • #3
      Re: Avg. Sump Pump discharge rates???

      Some questions for thought. Understand that I know absolutely nothing about where you live.

      - Why is there so much ground water coming in.
      - Is there a chance that there is a leaking main somewhere
      - Who suggested the size of the dry-well. Should it be bigger?
      I have other questions but they will come later


      • #4
        Re: Avg. Sump Pump discharge rates???

        I live in Indianapolis IN There has been little to no rain latley, I looked at both mine and my neighbor's water meter and see no flow when nothing is in use in the house. (not saying it couldn't be somewhere else) I just guessed on the size of the dry well. I figured 50 gallons would be enough... Guess not.


        • #5
          Re: Avg. Sump Pump discharge rates???

          There is no average discharge rate. Different pumps have different flow characteristics. The chart below shows the performance curve of a .3 horse power dewatering pump.

          As you can see, the performance depends on the height the effluent (water) has to rise from inlet to outlet.