So I had a home inspected this evening and noticed something I have never seen before. The hole is about 15ft deep! It looks like it was drilled out and then encased with concrete. The pump has a long PVC pipe that stretches all the way up and to the exterior or the house.

Why would anyone do this?

  • 1
    A larger sump pit permits more water to accumulate -- either to run the pump more efficiently, or to deal with the expectation of sudden surges. It's also possible that they're hoping the sump will act as a dry well, or conversely that they're trying to lower the local water table enough that it never reaches the point where the basement gets wet. Or... This is all speculation, and as my inspector said sometimes it's for a reason you'll never guess, or no good reason at all. (His example was an unexpected sewage clean-out that actually turned out to be a disguised safe.)
    – keshlam
    Jul 25, 2015 at 2:13

1 Answer 1


To remove water below the basement.

To provide a significant amount of storage in the event that the pump fails, allowing some time to correct the problem (depends on the inflow rate, but more depth is more storage.)

Depending on the age of the house, it may actually have been the well supplying the house at one time, and was converted to a sump pit when the water supply changed to an alternate well or municipal supply.

  • I was pondering whether it might have been a matter of reusing a well...
    – keshlam
    Jul 25, 2015 at 4:48

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