Quick Answer:
If you see seepage on a basement wall after several days of rain, start with simple exterior checks: gutters and downspouts, low spots and storm inlets near the house, and the sump pump’s performance. Document where and when the water appears over the next few storms. Take short-term measures only to reduce interior damage and follow the safety notes below. If seepage persists after the soil starts to dry or you spot interior mold, get a professional involved.
Why This Happens
Prolonged rain saturates the ground and increases hydrostatic pressure against foundation walls. If the exterior drainage system—gutters, downspouts, grading, or nearby storm inlets—is blocked or undersized, water ponds near the foundation and finds weak spots to enter. A sump pump can help, but it can be overwhelmed or fail when inflow exceeds its capacity or the discharge is limited. Municipal storm systems can also back up during long events and push water toward low-lying properties.
If this becomes a repeat problem, compare patterns to other scenarios like Backup worsens every rainy season or a surge from large city storms such as Backup after city storm event to determine whether the issue is local to your yard or part of a larger drainage overload.
Step-by-Step What to Do
1. Check gutters and downspouts for continuous overflow
- After the rain, inspect gutters for debris and sagging sections that cause overflow. Remove leaves and clean blockages.
- Look at downspouts where they meet the ground—if water pours full and close to the foundation, repair elbows or extend leaders so discharge goes several feet away from the house.
- Temporary tip: add a downspout extension or a flexible leader to move water away while you plan a permanent fix.
2. Inspect property low spots and blocked storm inlets near the house
- Walk the perimeter and yard to find areas that hold water and any clogged street or yard inlets. Clear leaves, mulch, and sediment from grates and inlets.
- Check soil grade near the foundation. Topsoil that slopes toward the house traps water; a clear outward slope helps surface runoff.
3. Verify sump pump runtime and consider temporary increased discharge
- Observe the sump pump during a rainfall: note how often it runs and whether it can keep up. Test it by pouring water into the pit (only if dry) to ensure the float and pump start reliably.
- If the pump is running constantly, make sure the discharge line is clear and routed away from the foundation. A temporary longer hose to send water further downhill can reduce near-foundation saturation—avoid directing discharge into neighboring properties or blocked storm systems.
- Confirm the pump has a working check valve so water doesn’t flow back into the pit between cycles.
4. Document water intrusion patterns over several rain events
- Take photos and note the location, timing (early rain, peak, or near the end), and severity of seepage each time it happens. Use the same reference points so you can compare.
- Track whether water appears only during heavy storms, during prolonged light rain, or after municipal drainage systems report capacity issues. This helps identify whether the failure point is gutters, yard drainage, sump capacity, or an external system.
What Not to Do
- Do not mix household chemicals to try to clear drains—that can create dangerous reactions and won’t fix exterior seepage.
- Avoid short-term “fixes” like stacking tires or leaning heavy objects against the foundation; these do not stop water and can cause damage or safety hazards.
- Don’t ignore ongoing seepage. Call a professional when seepage fails to abate after the ground begins to dry or when interior mold appears.
When to Call a Professional
- If seepage continues after the surrounding soil has had time to dry and you’ve ruled out surface clogs and gutter problems.
- If you see mold, persistent dampness inside, crumbling mortar, or new cracks in the foundation—these require prompt inspection and repair.
- If the sump pump runs continuously, cycles too often, or the electrical system is affected. Also call a pro if the problem seems tied to municipal backup or if repairs will involve landscaping changes, French drains, or foundation work.
Safety Notes
- Electric shock risk: avoid standing water in basements if any outlets or appliances are submerged. Cut power at the breaker only if you can do so safely and know where the main panel is.
- Wear boots and gloves when inspecting soggy areas. Contaminated runoff can carry bacteria and chemicals.
- Don’t climb on wet, muddy slopes or unstable ground. If structural damage or large cracks are present, keep a safe distance until a professional assesses the risk.
Common Homeowner Questions
- Q: Is one rainy event enough to call a pro?
A: Not usually. Start with the checks above; call a pro if seepage continues after soils dry or if you see mold or structural signs. - Q: How far should downspouts discharge from the foundation?
A: Aim to move water several feet away and onto a slope that directs runoff away from the house, without dumping it into a neighbor’s yard or a blocked inlet. - Q: Will a larger sump pump fix the problem?
A: It can help if the pump is undersized, but only after addressing gutters, grading, and blocked inlets; a larger pump alone may not solve the source of the inflow.
More in this topic
For more related fixes and similar symptoms, see Basement Drain Backs Up Only After Rain.