Our home (with basement, built in 1999) has a sump pump that was installed by the previous owner. In our area, runoff from melting snow in the spring or when the neighbors leave for a weekend with their sprinklers on usually when we see water there.
The sump is about two feet deep, and the float is adjusted such that there can be 18" or so of standing water in the sump before the pump turns on. It isn't uncommon for there to be 12" of water in the sump for a week at a time, without the pump running. I don't know if the depth of this sump was determined by calculation or solely by what was in stock at Home Depot that weekend.

Is this a situation where making the sump deeper would have a benefit?

Part of me wants to dig that sucker much deeper, so that the water level is as far below the basement slab as possible. If I'm seeing water so close to the bottom of the slab in this one spot, that means it's very close to the bottom of the slab in most of the basement, right?

On the other hand digging the sump deeper, aside from the work, means that the pump might be running more than required, and perhaps cycling more often than needed.

What would you do?

  • Is there any visible sign that water is coming in contact with your slab? moist areas, efflorescence, etc.?
    – Steven
    Mar 21, 2014 at 15:57
  • 1
    @Steven, there is some slight efflorescence around some of the small cracks in the slab, but I don't know if that was the first clue to the previous homeowner to put in the sump, or if has occurred since the sump was installed. I do have have an epoxy floor coating in the storage room that is flaking slightly in one spot; whether that's due to moisture or improper surface prep, I don't know. Aside from those, I don't see any obviously moist areas.
    – spuck
    Mar 21, 2014 at 16:09

2 Answers 2


I would not want to see 12 inches of standing water close to the slab grade in a sump pit. My first thought would be to see if you could adjust the float of the pump to turn on much sooner and keep the level down to maybe 4 to 6 inches. There should be an upper and lower level set on the pump. it would be helpful to know the make and model of the pump so we could check the specs and see if it can be easily adjusted. Keeping water standing so close to your slab can saturate your floor and cause weeping through spider cracks. I'd prefer to see the level at or below the level of the drain tile where it enters the pit.

  • I will have to look at adjusting the float. Judging from the craftsmanship of other DIY projects I inherited with the house, I would be surprised if there is any drain tile in the pit. The previous homeowner told me that they had installed the sump only a few years before, so I bet dollars to donuts that they cut a hole in the slab, put some gravel in the hole, and put in the sump liner.
    – spuck
    Mar 24, 2014 at 15:16
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    Fairly easy to tell. Pump it down and look for the drain tile entering the pit. Water should flow freely from the tile to the pit for the pump to get rid of. Also, how far away from the house does the pump exit the water?? Often a problem when a pump just dumps it by the foundation just to come right back in. Mar 25, 2014 at 11:56

I like to see a sump at least 30 inches deep by at least 30 inches by 30 inches. This way the pump runs a lot less and will last a lot longer. Over the years I have found that the floats are best adjusted so the water cover the impeller. By this I mean where the pump base is. It keeps it always moist and never becomes dry. So there is no danger of the impeller becoming stuck.For myself I have never lost a pump and still have the stand pump I bought 46 years ago. I only switched to a submersible pump because it is less noisy and more efficient. That is my take on it and it seems to work. Pete

  • Sorry I should have said , I like to see the base of the pump covered when the pump stops . Pete Apr 11, 2017 at 1:45

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