Water in the crawl space
Short answer
If your crawl space has standing water, it’s not normal. You can have damp soil under your liner, but the top of the liner should stay dry. There are typically four sources of water in a crawl space: water getting in from outside, a high water table, a plumbing leak or condensation. When the water shows up usually tells you which one it is, and that points to the right solution.
On this page
Where the water comes from
I always ask the homeowner when they notice the water. That usually gives me an idea of what the problem is.
| What you notice | Likely source | Where to look |
|---|---|---|
| Water only after rain | Water getting in from outside | Downspouts, gutters, ground slope, access doors, gaps around pipes, exterior walls |
| Water coming up from below, in low spots or at foundation joints, sometimes days after the rain and across much of the floor | High water table | Low spots and where the floor meets the foundation |
| Very localized water that doesn’t follow the weather, often near pipes and after a shower, the dishwasher or the washing machine | Plumbing leak | Supply and drain lines overhead |
| Drops spread over cold ducts and pipes, high humidity and no clear way in for water | Condensation | Ducts, cold water lines, humidity readings |
- Rain water from a downspout and ground sloping toward the house
- A high water table pushing water up from below
- A plumbing leak
- Condensation on a cold duct
How much water is normal?
As far as standing water goes, there should be none. I don’t think it’s normal to have puddles in a crawl space. There can be some moisture in the ground under your vapor barrier, and that’s OK. For humidity, I use the same levels as always: under 60% is good, 60% to 65% I monitor, and if it’s over 65% for an extended period, I want to investigate. See crawl space humidity.
Crawl space waterproofing: fixes from simple to major
First question: can we keep the water from getting in? If it’s coming from a gutter or a downspout, ground that slopes toward your home or an AC condensate line draining into your crawl space, I solve those problems. See gutters and downspouts and grading around the foundation. I don’t install a French drain because your downspout ends next to your house. I use an interior drainage system with a sump pump when I see these signs:
- Groundwater getting in again and again
- Water where the floor meets the foundation wall
- A high water table
- Several entry points
- Ground outside that can’t be corrected enough
- Recurring flooding
More on French drains and sump pumps.
After a flood
Make sure you’re safe. Before anyone goes in, check for electrical and gas hazards, make sure the structure is sound, and consider whether the water could be contaminated or include sewage. If the water may be contaminated, treat it as if it is. I don’t encapsulate right after a flood. I want to see how the space dries out first.
After a flood, the CDC advises never turning the power on or off, or using electrical tools, while standing in water. If the water came from sewage or was otherwise contaminated, the EPA says to call in a professional.
Once it’s safe, this is the order I follow:
- Stop the source, if possible.
- Pump out the water.
- Remove debris, and wet porous materials when they can’t be saved.
- Dry the space. The EPA recommends drying water-damaged areas within 24 to 48 hours to prevent mold growth.
- Measure the moisture in the wood.
- Have the HVAC and electrical checked.
- Find out what let the water in.
Sources
- Centers for Disease Control and Prevention, Safety guidelines: reentering your flooded home.
- U.S. Environmental Protection Agency, Mold cleanup in your home, updated June 4, 2026.
- U.S. Environmental Protection Agency, A brief guide to mold, moisture and your home.