Basement Leaking When It Rains? What to Do
Short answerBasement leaks often begin with water collecting near the foundation, so start with gutters, downspouts and the slope of the soil. Kansas State also points to high water tables and poorly installed footing drains. Dry things within 24 to 48 hours. If water still comes in, get a professional opinion before buying a waterproofing system.
Safety first
- Do not walk through water if outlets, cords or appliances may be wet. Have the power to the basement shut off first, by the panel only if you can reach it from a dry floor, or by your electric company.
- If the water smells like sewage, stay out and call a plumber or your sewer utility. Sewage cleanup needs extra care.
- If gas appliances are in the water, or you smell gas, leave and call the gas company from outside.
Likely causes
| Cause | How to tell | What fixes it |
|---|---|---|
| Clogged gutters or short downspouts | Water shows up at one spot during rain, next to a downspout or an overflowing gutter. | Clean them twice a year, and extend downspouts at least 5 feet from the foundation. |
| Soil sloping toward the house | Puddles stay against the wall, or backfill has settled. | Add soil so the ground slopes away. Keep slope checks part of your yard routine. |
| Window wells or cracks | Water enters at a basement window, or through a wall crack. | Keep wells drained or covered. Have a contractor seal the crack. |
| High water table or failed footing drain | Water comes up at the floor and wall joint or through the floor, and lasts well after rain. | A contractor checks the drains and may suggest a drain and sump system. |
| Sewer backup | Water comes up from a floor drain, often in heavy rain, with a bad smell. | Call a plumber about the line and a backflow valve. |
| Condensation, not a leak | Damp walls or floors in humid weather, with no rain involved. | Lower indoor humidity with a dehumidifier. |
Why this is a job for a professional
- Water still comes in after the gutters, downspouts and slope are corrected.
- You see cracks that are growing, or a bowing wall. See a structural engineer.
- There is sewage, or mold over about 10 square feet.
- Ask: where exactly is the water entering, and how do you know? Did you check drainage outside first? Where will the drain outlet or sump discharge? What happens during a power outage? What does the warranty cover?
What it costs to have fixed
Basement Waterproofing is estimated at $2,450 to $15,500 nationally. See your state
Common questions
Why is my basement leaking when it rains hard?
Usually, roof water and surface water are collecting next to the foundation. Check for overflowing gutters, short downspouts and ground that slopes toward the house before you assume the basement needs major work.
How far should downspouts carry water from my house?
University of Nebraska Extension says at least 5 feet from the foundation. Add a splash block or another way to keep the soil from washing out.
How much slope do I need around my foundation?
Kansas State suggests about 1 inch per foot for 15 feet as ideal, and at least 6 inches in 10 feet to maintain as the soil settles.
Is installing footing drains in an old house expensive?
Yes, Kansas State calls it quite expensive and disruptive, because it means digging outside or breaking up the floor inside. That is why it makes sense to fix the outside drainage first.
Can you seal a basement leak from the inside?
Interior sealers help only so much. Kansas State University says they can reduce water vapor passing through walls, but that the most reliable option is often to excavate the outside wall and coat it. We recommend fixing outside drainage first and getting a professional opinion if water keeps coming in. Source
Does flood insurance cover a basement?
Only in a limited way. FEMA says National Flood Insurance Program coverage in a basement is limited to specific items, such as furnaces, water heaters, sump pumps and electrical boxes, plus cleanup. Finished floors and walls and personal items such as couches and televisions are excluded, so read your own policy. Source
Related repairs
- Door Won't Close? How to Fix a Sticking or Sagging Door
- Foundation Cracks: Which Are Serious and What to Do
- Garage Door Spring Broken? Stop and Read This First
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- Gutters Overflowing? Why It Happens and How to Fix It
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- Mold in Bathroom? How to Clean It and Keep It Away
- Roof Leak? What to Do Now and When to Call a Roofer
Last verified 2026-11-01
Sources
- Kansas State University: Dry Basements and Crawl Spaces — Water sources, slope away from the house, footing drains and their cost, sewage backups, window wells, regular checks in the wet season, and condensation
- University of Nebraska Extension: Publication G2186 — Cleaning gutters twice a year and extending downspouts at least 5 feet
- FEMA: Protect Your Home From Flooding — Maintaining gutters and grading, closing cracks, and keeping floor drains clear
- CDC: About Mold — Drying flooded areas within 24 to 48 hours
- NC State Extension: Inspecting a House — Stains, damp walls, musty smell and saturated soil as signs of basement water
- EPA: A Brief Guide to Mold, Moisture and Your Home — The 10 square foot mold figure
General information, not professional advice. Conditions, codes and prices vary. Turn off power, gas or water before any work, and hire a licensed professional when in doubt. Cost figures are our estimates, not quotes.