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The crawlspace under our house has a tendency to get a bit muddy when the rains are heavy and then dry up a few days later. When the rains are especially hard water will collect in a pit in the crawlspace and I have to go in with a wet vac to clear out the puddle that has formed.

I've had this explained to me by a contractor as the high water table which comes and goes with the tide (I live in Berkeley, CA) and not something to worry about. Other contractors are pointed it out as a concern. Our neighbors have a sump pump to keep their basement dry.

How do I know if I need a sump pump? What are the risks of not getting one right away? How hard is it to install myself? The house is 100 years old, I assume it's been standing this whole time without one.

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A sump is easy enough to install DIY. You need a precast concrete sump well (mostly to keep muck out of the pump,and keep the float switch clear), a pump, a place to dump the water to, and a GFCI electrical outlet. In general the water needs to dump outside, not to a sewer.

In Berkeley CA you likely have heavy clay soils that don't drain quickly. The tides seem an unlikely source of your problem.

As to effect on the home: wet soil expands somewhat compared to dry soil. If only part of the crawl gets wet, that can create differential stresses on the foundation, leading to uneven settling and cracking.

The problem can also be solved with perimeter drains, keeping the water outside in the first place.

One issue you'll face is it's hard to find a good quality sump pump that has low capacity. The smaller (capacity) pumps tend to be cheaper (quality) pumps.

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    It sounds like you're suggesting the water is probably coming from an outside source? If so then I should be taking a closer look at how the gutters are draining around the house? Is the high water table explanation likely?
    – Jeff Wu
    Commented May 4, 2014 at 21:08
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    Berkeley has clay soils and often high water tables. Dig a hole to find your local water table. But given that you have rain based event, you likely have a surface water contribution to the issue.
    – Bryce
    Commented May 4, 2014 at 23:11
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It sure seems to me that a sump pump would be a good idea, especially if you don't want to keep drying it with a wet vac. I am assuming the pit you speak of is of some solid material, not just a hole in the dirt?

A sump pump is pretty easy to install. A small one with a built in float connected to some tubing running out of the crawl space would do the trick. You just need to supply some electricity, set the pump on the bottom of the pit, connect the hose/tubing and your basically done. It will work automatically when the water raises the float.

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  • The pit is a 2 foot deep excavated pit in the dirt. It's about 6x6 in area.
    – Jeff Wu
    Commented May 4, 2014 at 21:06
  • You would need to line the bottom of the pit with brick, patio block or crushed stone so the pump won't suck up mud and foul the impellers in the pump.
    – shirlock homes
    Commented May 5, 2014 at 10:14

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