You walk outside after a big storm, pop open the crawl space hatch, and there’s water down there. Should you worry?
Not always. A day or two after heavy rain, some water under a house is pretty normal. If the water is still sitting there 3 days after the last rain, or shows up again after every storm, you’ve got a problem worth a phone call. We call this the 3-day rule.
We see this a lot in North Georgia. Our red clay holds water, and summer storms here dump a lot of rain fast. So homeowners end up staring at a wet crawl space, unsure whether to wait or call someone. This post walks you through the test, what the water is telling you, and who to call.
Let us jump to the topic!
What Is the 3-Day Rule for Water in a Crawl Space?
Simple version: water still standing 3 days after the last rain means you call a crawl space contractor. Water gone by day 3 means you wait, then look again after the next big storm.
Why 3 days? After a storm, rainwater soaks into the ground and drains off once the rain stops. When water hangs around past day 3, something other than the storm is feeding the water. Usually we find groundwater coming up from below, a drain system that stopped working, or a leaking pipe.
The test takes about two minutes of your time, spread over 3 days. Note the date of the last rain. Open the hatch and snap a photo of the water, with a brick or a tape measure in the shot so you know the depth later. On day 3, go back and take another photo from the same spot. Then put the two side by side.
Hang on to both photos, by the way. Any contractor you call will ask to see them.
Not sure what you’re looking at? Use this table.
| Normal | Not normal |
| Damp soil after a storm | Standing water on day 3 |
| A puddle gone within 3 days | A waterline on piers or walls |
| Sweating cold water pipes in summer | Water on top of the vapor barrier |
| Dry ground between storms | Soil wet between storms, or water back after every storm |
How Much Water in a Crawl Space Is Too Much?
Time is one part of the picture. How much water you see, and where, matters too.
A little damp soil, or a thin wet film in one low corner, sits at the mild end. The dirt looks dark and wet, but nothing pools. Run the 3-day test and don’t stress yet.
Puddles in a few spots are a step up. So is a single pool deeper than the sole of your shoe, or water resting against a pier or the foundation wall. Do the 3-day test here too, but check your gutters and downspouts today instead of waiting.
Now, if water covers most of the floor, or you find water sitting on top of the vapor barrier, skip the waiting. Same goes for a waterline on the walls or piers from past floods. Call now.
And water near wiring, the furnace or ductwork? Call right away, whatever the amount.
Want the bigger picture of crawl space damage, from minor issues to structural ones? Our post on how bad is your crawl space is covers the full range.
Where Is the Water Coming From?
Pay attention to when the water shows up. Timing tells you more about the source than almost anything else.
Water After Storms Which Clears by Day 3
Most of the time this is surface water. A clogged gutter spills over. A downspout dumps a whole roof’s worth of rain right beside the foundation. Or the yard slopes toward the house instead of away. We wrote about both how poor yard drainage damages your foundation and whether I should fix grading or waterproof my foundation first.
Water Which Fails the 3-Day Rule
This one is usually groundwater. Red clay drains slowly, so after a wet stretch the soil under your home stays soaked and the water pushes up into the crawl space. Sometimes you’ll even see water seeping up through the dirt floor.
A longer downspout won’t fix groundwater. You need a drain system, inside or outside the foundation, put in by a crawl space contractor.
Water With No Rain at All
Dry week, wet crawl space? Then rain isn’t the cause, and the 3-day rule doesn’t apply. Start with the pipes. A leaking supply line or drain pipe is the first thing we check. A water heater or softener sitting in the crawl space is another usual source, and so is an HVAC condensate line that came loose. In summer, cold water pipes sweat and drip too.
For any leak, call a plumber before anyone else.
Is Water Under the Vapor Barrier a Problem?
The vapor barrier is the plastic sheet lying over the dirt floor. The sheet is there to keep ground vapor out of the air under your home. So you lift a corner and find damp soil or a bit of condensation underneath? Normal. The sheet is working.
Water on top of the sheet is another matter. Water up there comes from somewhere else, like a leak, a crack in the wall, or groundwater forcing through the seams. This is the water to run the 3-day test on.
When you look under a corner, damp dirt is fine. Small pools near the walls under the plastic are worth a second look after the next storm. Water coming up through the seams and onto the top means you call a contractor. And torn or loose sections letting water through need repair either way.
Before you touch anything wet, shut off power to any equipment down there: gloves and a mask help. If water is touching wiring, stay out.
We cover barrier types and installation in our vapor barrier installation post.
What Happens If Water Stays Past 3 Days?
Short answer: damage builds up slowly, out of sight.
The wood suffers first. Joists and sill plates soak up water and weaken over months (more on how to stop wood rot under your house). Your indoor air comes next, since air from the crawl space rises into your rooms and brings a musty smell along. See why your house smells musty after rain and crawl space mold and your health.
Pests tend to show up last. Termites, roaches and mice all go for damp wood and wet dirt.
What to Do Between Day 1 and Day 3
Day 1 is about safety and clues.
- If water touches wiring, outlets or any equipment, stay out. Flip the breaker or call an electrician first.
- Take photos and write down the date.
- Walk around outside. Clear any clogged gutters and turn the downspouts away from the house.
- Rule out a plumbing leak. With every tap off, watch the water meter for a minute. Meter still moving? You’ve got a leak, so shut the main and call a plumber.
Day 2 is the hard one, because the right move is to do nothing. Don’t pump the water out with a shop vac. Doing so hides the answer to the test.
On day 3, go back to the same spot and take your second photo. Water still there means you call a crawl space contractor. Water gone means you keep watch after the next heavy rain.
Thinking about insurance? Coverage turns on where the water came from, so read whether your homeowners insurance covers crawl space repair before you file anything.
Who Should You Call for Water in a Crawl Space?
Not every wet crawl space is a job for us, and we’d rather tell you so up front.
Water with no rain, or a meter that keeps moving with every tap off, is a plumber’s job. A flood from a burst pipe, or water with sewage in the mix, goes to a water damage restoration company. Call a crawl space or waterproofing contractor when the water fails the 3-day rule, comes back after every storm, or rises out of the ground.
Tri-State Waterproofing has worked on crawl spaces across North Georgia for more than 20 years. When our crew comes out, we inspect the space, track down where the water comes from, and test the framing for soft wood. You get a written plan and a price before we start anything. We cover Gainesville, Athens, Woodstock, Marietta, Dawsonville and the metro Atlanta area.
Book a free inspection on our crawl space repair page, or call (770) 869-7888.
Frequently Asked Questions
Is water in a crawl space a problem when selling a house?
Yes, most of the time. A home inspector will look in the crawl space, and standing water ends up in the report. Buyers then use the report to push for repairs or a lower price. A finished repair with receipts and a transferable warranty gives them far less to push back on.
How much does it cost to fix standing water in a crawl space?
Depends on the source. Fixing gutters and downspouts is the cheapest route, and an interior drain system costs more. For a rough number, a sump pump install by itself runs $1,200 to $1,800 for most homes (see our sump pump installation guide). Damaged framing raises the total. Our free inspection gets you a real price for your house.
Should an encapsulated crawl space have water after a storm?
No, not even on day 1. Encapsulation seals the floor and walls with a liner. Water inside after a storm points to a failed seam, a wall problem, or a drain system that stopped working. Call whoever installed the system. To learn how these systems work, read whether crawl space encapsulation is worth the cost.
Does a dehumidifier remove standing water from a crawl space?
No. A dehumidifier pulls water vapor out of the air. Pooled water needs drainage. Our post on whether an encapsulated crawl space needs a dehumidifier explains when one helps.
The 3-Day Rule, Once More
Water gone within 3 days? Keep watch after the next storm. Still there on day 3, or back after every heavy rain? Give us a call.
Reach Tri-State Waterproofing at (770) 869-7888, or fill out the form on this page to book a free crawl space inspection.
