I'm looking to replace my sump pump because the last rain storm showed that my sump pump couldn't handle the amount of water. It ran continuously for about an hour or two with the water level still rising.

My basin is 13" diameter at the bottom and 22" high.

I was looking at a Wayne pump and all of them point to the same documentation: https://www.waynepumps.com/wp-content/uploads/woocommerce_uploads/2018/10/600002-001-D.pdf

It states that a minimum of 22" height is needed.

My question is why is the 22" height needed when the sump pump itself is 11.5" high by 9" wide?


Some of the reasons might be:

  1. The height is needed for the float which contains the switch to rise to a vertical position to turn the pump on. If the pump was in a shallow hole, the float would not turn on until the water level in the room was 22" above the pump.
  2. Also if the sump basin is too shallow, the pump would turn on and off more often. This will wear the switch contact out from the frequent arcing.
  • I called them manufacturer and it was definitely for a tether float; however, it doesn't apply with the vertical float, which only needs the height of the sump pump. The inlet is lower than the vertical float as well. Seems odd their documentation didn't call this out as it's a definite difference.
    – kevindaub
    Aug 17 '20 at 18:12

Two things:

  1. It allows room for the inlet(s) to the sump pit. If the pit were too shallow the water might backup into the inlet pipe before the pump switches on.
  2. It gives the pump a bit of "buffer" when you have sudden surges of inlet water. If you didn't have that, it might overflow before the pump turns on and gets a flow going.

Also, check that your outlet pipe has enough capacity. That might be the real problem instead of the pump. You can only force so much flow through a small pipe.

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