Why is there water under my house?
Water under a raised house usually comes from outside: rain draining toward the house instead of away, downspouts emptying next to the foundation, or a high water table after heavy rain. A leaking supply pipe, drain line or AC condensate line can also be the cause. On a slab home, water shows up as damp floors or wet carpet along an outside wall. Find out whether it's rainwater or a plumbing leak first, because the fix is completely different.
- Urgency
- Address soon
- DIY
- Some steps you can try
- Typical cost
- $500–$8,000
- Time
- A few hours for a leak
Address it within weeks, not months. Constant moisture under a house rots wood framing, draws termites and raises humidity indoors. If water is rising quickly or reaching wiring or ductwork, treat it as urgent.
What's happening
On a pier-and-beam house, the crawlspace is the lowest point on the lot, so water that runs toward the house ends up there. If it shows up only after rain, it's drainage. If it's there in dry weather, something under the house is leaking.
Most likely causes
- 01Ground sloping toward the house
Soil that has settled or been built up the wrong way sends rain straight under the house.
- 02Downspouts dumping at the foundation
Roof water dropping right at the wall soaks the ground and pours into the crawlspace.
- 03High water table
After long, heavy rain the ground is full and water can rise into a low crawlspace. Common in flat, low-lying areas near the Gulf.
- 04A plumbing leak
A supply line, drain pipe or water heater line leaking under the house. Water in dry weather is the giveaway.
- 05AC condensate line
The line that drains water from the air conditioner can come loose or empty under the house instead of outside.
What you can try yourself
- 1Check whether the water appears only after rain or in dry weather too
- 2Turn off all water in the house and watch the water meter for 30 minutes. If it moves, there's a leak
- 3Look at where your downspouts empty and extend them away from the house
- 4Make sure the AC condensate line drains outside, not under the house
- 5Don't crawl into standing water near wiring or ductwork. Have a pro look
When to call someone
Call a plumber if the meter test shows a leak. Call a drainage contractor if water comes in with rain. Call a foundation specialist if floors are sagging, sills look soft, or you see rotted framing.
What it should cost
$500–$8,000
Fixing a pipe leak or rerouting a condensate line is often a few hundred dollars. Regrading, French drains or a sump pump in the crawlspace usually run $1,500 to $6,000. A vapor barrier or encapsulation adds more, and rotted framing repairs are priced on their own.
Estimates are typical US ranges for orientation. Actual pricing varies by region, home and contractor — always get a written quote.
What happens if you wait
Months of standing water under a house rot sills and joists, attract termites, and push damp air up into the living space. Fixing framing damage costs far more than fixing the water.
Questions to ask the contractor
- Is this rainwater, groundwater or a plumbing leak, and how do you know?
- Will you fix the slope outside, drain the crawlspace, or both?
- Do I need a sump pump, and where would it empty?
- Did you see any rot, sagging or termite damage while you were under there?
- Would a vapor barrier help in my case?
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Last reviewed November 8, 2026. General guidance only — it can't replace an inspection of your actual home by a qualified professional.