There is a sump pump in the basement, in a basin, with a power cord going into it, and a pipe going out of it. How can I test the various kinds of functionality of this setup?

I can put a bucket of water into the sump and see if the pump starts - I suppose that tests the float switch, etc. How low should the water level in the sump be before it turns off?

But how do I actually test that it is doing its job of keeping water out of where it's "not supposed to be"?

1 Answer 1


There are typically "sliders" or some sort of adjustment that mark the "start" and "stop" (or "high" and "low") water levels.

Generally there's no minimum low-water level other than you want to make sure that there is always water covering the pump intake (so it doesn't suck air).

The "high" mark just needs to be low enough that water never gets out of the sump. If you have a "high water" alarm (and you should), make sure the "high" mark is low enough that it doesn't trigger by accident.

Other than that, the further apart they are spaced, the less frequently it will turn on and the less wear on the pump (start-up is the most stressful time). Too close together and any backwash down the output pipe could cause it to turn back on again in an endless cycle.

For testing, dumping buckets of water down is fine, as is using a hose to fill it. You just want to make sure that it turns on and off within the limits described above.

  • 1
    I think you could clarify your point a bit: It's not that there SHOULD always be water covering the intake (it's perfectly fine for the pit to be totally empty), but your "off" set point needs to be higher than the point at which the pumps sucks air, otherwise it will never turn off.
    – gregmac
    Oct 26, 2012 at 20:26
  • Good point, though it's not just that... Some water pumps can burn out if they suck air. Oct 27, 2012 at 2:26
  • Good answer. You might add testing the check valve, by ensuring minimal water drops back into the pit after the pump finishes. That, and clean all the gunk out.
    – Bryce
    Oct 27, 2012 at 4:22
  • I guess the real question I have is how do I test to make sure that the surrounding area/earth is draining water correctly to the sump pit?
    – Aaron
    Oct 30, 2012 at 21:40
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    @BrianWhite: For some pumps, if using a check valve, one must have a small hole in the pipe between the check valve and the pump. Otherwise, if the sump dries out while there's water sitting on the check valve and then later fills, the pressure of water sitting on the check valve may prevent the rising water from displacing enough air in the pump to make it effective.
    – supercat
    Jan 20, 2015 at 22:32

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