How to repair a basement leak?

First, find the source — is water coming through a wall crack, the floor-wall joint (cove joint), a window well, or the floor itself? For wall cracks: clean the crack and inject polyurethane foam or apply hydraulic cement. For cove joint seepage: apply waterproofing sealant along the joint or install an interior French drain system. For window wells: install window well covers and improve drainage with gravel. For floor seepage: apply a basement waterproofing coating or install an interior drain tile system with a sump pump. Always address the root cause (exterior drainage, gutters, grading) to prevent recurrence.

How to repair a leaking basement wall?

For minor wall cracks (under 1/4 inch): clean the crack with a wire brush, apply hydraulic cement for active leaks or epoxy/polyurethane injection for dry or damp cracks. Polyurethane is preferred for waterproofing because it stays flexible and cures even in wet conditions. For seepage through the wall surface (not a specific crack): apply a crystalline waterproofing coating like Xypex or Drylok to the interior wall surface. For persistent wall leaks, the long-term solution is exterior waterproofing — excavating around the foundation and applying a waterproof membrane and drainage board.

How to repair leaking basement walls?

Multiple leaking walls usually indicate a systemic drainage problem rather than isolated cracks. Check your gutters (extend downspouts 4-6 feet from the house), regrade the soil to slope away from the foundation (6 inches over 10 feet), and inspect window wells for proper drainage. For interior treatment, apply Drylok or similar basement waterproofer to all walls — two coats with a brush, forcing the product into pores. If walls continue leaking after exterior drainage improvements, you likely need a professional interior drain tile system ($3,000-8,000) connected to a sump pump.

How to repair basement leaks?

The approach depends on the source. Wall crack leaks: inject polyurethane foam or fill with hydraulic cement ($20-80 DIY). Floor-wall joint leaks: seal with polyurethane caulk or install interior drain tile ($3,000-8,000 professional). Window well leaks: add gravel drainage and install covers ($30-100). Floor leaks: apply waterproofing paint or install a sump pump ($200-600 DIY, $1,000-3,000 professional). The most important step is identifying and fixing the exterior drainage issue causing the water pressure — no interior fix is permanent if water keeps pressing against the foundation.

How to repair a basement wall that is leaking?

Start by determining if the leak is from a visible crack or general seepage. For a crack: clean it out, let the surface dry slightly, and inject polyurethane foam (best for active leaks) or fill with hydraulic cement (fast-setting, even underwater). For general seepage through the concrete surface: the concrete is porous and water is being forced through by hydrostatic pressure. Apply a crystalline waterproofing product or masonry waterproofer like Drylok to the interior. Long-term, address exterior drainage to reduce water pressure against the wall.

Can I fix a basement leak myself?

Yes, most minor basement leaks are DIY-fixable. Small wall cracks: hydraulic cement or injection kits ($20-80). Seepage: waterproofing paint/coating ($30-60 per gallon). Window wells: covers and gravel ($30-100). Even a basic sump pump installation is a manageable DIY project if you're comfortable with plumbing. However, call a professional for: leaks caused by bowing walls, leaks from multiple sources simultaneously, leaks that return after DIY repair, or any leak accompanied by structural cracking. Professional waterproofing costs $2,000-10,000 but includes warranties of 10-25 years.

Will a basement leak get worse over time?

Almost always, yes. A small leak means water has found a path through your foundation — and water always widens its path. Freeze/thaw cycles expand cracks. Constant moisture deteriorates concrete and mortar. Mold can develop within 24-48 hours of moisture exposure and spread quickly. The water pressure causing the leak (hydrostatic pressure) doesn't decrease on its own. What starts as a damp spot can become standing water, mold contamination, and structural damage. Early repair when the leak is small saves significant money — a $30 DIY fix now can prevent a $5,000+ professional repair later.

Does homeowners insurance cover basement leaks?

It depends on the cause. Generally NOT covered: gradual seepage, groundwater infiltration, foundation cracks from settling, poor drainage, and general waterproofing. Generally COVERED: sudden, accidental events — such as a burst pipe flooding the basement, a sump pump failure (if you have sump pump coverage rider), or water backup from a city sewer line (requires sewer backup rider). Flood damage from external sources (river, storm surge) requires separate flood insurance through FEMA's NFIP. Document all damage with photos and contact your insurer immediately to check your specific policy.

How much does it cost to fix a basement leak?

DIY crack repair: $20-80 per crack. DIY waterproofing paint: $30-60 per gallon (covers ~75 sq ft). Professional crack injection: $250-800 per crack. Interior French drain system with sump pump: $3,000-8,000. Exterior waterproofing (excavation + membrane): $8,000-15,000. Full interior + exterior waterproofing: $10,000-25,000. Costs vary significantly by region and the severity of the problem. Always get at least 3 quotes from licensed waterproofing contractors. Be cautious of extremely low bids — quality waterproofing requires proper materials and experienced installation.

What is the best basement waterproofing method?

For most homeowners, the best approach is a combination: (1) Fix exterior drainage first — extend downspouts, regrade soil, clear window wells. This alone solves 60-70% of basement moisture problems and costs $0-500. (2) Seal visible cracks with polyurethane injection. (3) Apply waterproofing coating to interior walls. If leaks persist, an interior drain tile system with sump pump is the most cost-effective professional solution — it manages water rather than trying to block it. Exterior waterproofing membrane is the "gold standard" but costs 2-3x more and requires excavation.

Basement Leak Repair: Find & Fix Leaks Permanently (2026)

How to Find Where Your Basement Is Leaking

Before you fix anything, you need to find where water is actually entering. This sounds obvious, but water can travel along walls and pipes before dripping — the wet spot you see may be several feet from the actual entry point.

Wall Cracks

The most visible leak source. Look for vertical, diagonal, or horizontal cracks in poured concrete walls. Even hairline cracks can allow significant water under pressure. Water will appear as a streak or wet line following the crack path. Active leaks may show mineral staining (white efflorescence) along the crack edges. See our foundation crack repair guide for detailed crack identification.

Cove Joint (Floor-Wall Joint)

The joint where the basement floor meets the wall is the most common leak location. In poured concrete basements, the floor and walls are poured separately — this cold joint is never truly watertight. Hydrostatic pressure pushes water up through this seam. You'll see water seeping along the base of the wall, sometimes all the way around the perimeter.

Window Wells

Basement windows with below-grade window wells often leak when the well fills with water during heavy rain. Check for: clogged window well drains, insufficient gravel drainage, no window well cover, or deteriorated window caulking. Window well leaks are among the easiest and cheapest to fix.

Pipe Penetrations

Anywhere a pipe, wire, or conduit passes through the foundation wall is a potential leak point. The gap between the pipe and the concrete is usually sealed with hydraulic cement or caulk — both of which degrade over time. Check around water lines, sewer pipes, electrical conduits, gas lines, and dryer vents.

Floor Seepage

Water coming up through the basement floor itself — not through cracks, but through the concrete. This indicates high water table and significant hydrostatic pressure pushing water up from below. Floor seepage is the most serious type of basement leak and usually requires a professional drain tile system and sump pump to manage.

Pro Tip

The aluminum foil test: Not sure if your damp wall is a leak or just condensation? Tape a 12-inch square of aluminum foil flat against the damp area with duct tape, sealing all edges. Wait 24 hours. If moisture is on the room-facing side of the foil, you have a condensation problem (fix with a dehumidifier). If moisture is between the foil and the wall, water is coming through the foundation — that's a true leak that needs repair. For step-by-step water leak fixes, see our basement water leak repair guide.

Common Causes of Basement Leaks

Understanding why your basement is leaking tells you where to focus your repair — and more importantly, how to prevent it from happening again:

Cause	What Happens	Fix
Hydrostatic Pressure	Groundwater pushes against foundation walls and floor	Interior drain tile + sump pump; exterior drainage
Foundation Cracks	Water enters through cracks from settling or pressure	Polyurethane/epoxy injection; hydraulic cement
Poor Surface Drainage	Soil slopes toward house, directing rainwater to foundation	Regrade soil, extend downspouts, fix gutters
Clogged Footing Drain	Original drainage tile is blocked or collapsed	Install new interior or exterior drain tile system
Window Well Issues	Wells fill with water, overwhelming window seals	Window well covers, gravel drainage, well drains
Lateral Pressure	Saturated soil expands and pushes walls inward	Professional: carbon fiber, wall anchors, or piers

Mold Warning

Any basement leak can lead to mold growth within 24-48 hours. If you see or smell mold, address it immediately. Small mold patches (under 10 sq ft) can be cleaned with a bleach solution. Larger areas require professional mold remediation ($1,500-5,000). Never ignore mold — it spreads quickly and can cause serious respiratory health issues, especially for children, elderly, and immunocompromised individuals.

DIY Basement Leak Repair Methods

Most minor basement leaks can be fixed with $20-100 in materials and a few hours of work. The key is matching the right repair method to your specific leak type. Here's a complete step-by-step approach:

Repair Method by Leak Type

Leak Type	Best DIY Method	Cost	Difficulty
Wall crack (active leak)	Polyurethane injection	$30 – $65	Moderate
Wall crack (dry)	Epoxy injection	$40 – $90	Moderate
Quick patch (flowing water)	Hydraulic cement	$8 – $15	Easy
Wall seepage (porous)	Waterproofing coating (Drylok)	$30 – $60/gal	Easy
Window well	Gravel + window well cover	$30 – $100	Easy
Pipe penetration	Hydraulic cement + sealant	$10 – $25	Easy

Find the leak source

This is the most critical step — fixing the wrong area wastes time and money. Start inside: look for water stains, damp patches, efflorescence (white mineral deposits), or active dripping. Check the floor-wall joint (cove joint), visible cracks, around windows, and where pipes penetrate the wall. Use the aluminum foil test: tape a 12-inch square of foil flat against a damp area. After 24 hours, check both sides. Moisture on the room-facing side means condensation (a humidity problem, not a leak). Moisture between the foil and wall means water is coming through the foundation.

Identify the repair method

Match the repair to the leak type. Active crack leak: polyurethane injection (cures in water, stays flexible). Dry crack: epoxy injection (structural bond, stronger than concrete). Quick patch on active flow: hydraulic cement (sets in 3-5 minutes, even underwater). General wall seepage: crystalline waterproofing coating (Xypex, Drylok). Cove joint leak: polyurethane sealant along the joint. Window well leak: improve drainage with gravel and install covers. Floor seepage: interior drain tile system (usually professional) or sump pump for water management.

Prepare and clean the repair area

Remove any loose concrete, old paint, or efflorescence with a wire brush. For injection repairs: widen hairline cracks to 1/4 inch using a cold chisel to create a proper channel. Vacuum all dust and debris. For waterproofing coatings: etch the concrete with muriatic acid solution (10:1) to open pores, then rinse thoroughly and let dry. The surface must be clean and free of paint, sealers, or oil for any repair product to bond properly.

Apply the repair

For crack injection: install injection ports every 6-12 inches, seal the surface between ports with epoxy paste, let cure 4-6 hours, then inject polyurethane or epoxy from bottom to top. For hydraulic cement: mix a golf-ball-sized amount until it starts to stiffen, then press firmly into the crack with a gloved hand or putty knife — you have 3-5 minutes of working time. For Drylok/waterproofing coating: apply with a thick-nap roller or stiff brush, forcing the product into concrete pores. Apply first coat to damp (not wet) surface, let dry 24 hours, then apply second coat.

Fix exterior drainage (the root cause)

No interior repair is permanent if water keeps pressing against your foundation. Check gutters: clean them and extend all downspouts at least 4-6 feet from the house using extensions or underground drain pipe. Regrade soil: the ground should slope away from the foundation at least 6 inches over the first 10 feet. Window wells: fill the bottom 6 inches with gravel for drainage and install clear polycarbonate covers. These exterior fixes are free or cheap ($20-100) and solve 60-70% of basement moisture problems without any interior repair needed.

Your basement leak repair is complete. Monitor during the next heavy rain and check monthly for 3 months to confirm the fix is holding.

Best Basement Waterproofing Products

These are the most effective DIY products for basement leak repair and waterproofing, tested and trusted by homeowners and contractors alike:

RadonSeal DIY Basement Crack Repair Kit

$34 – $65

Polyurethane foam injection kit designed specifically for basement wall cracks. Cures even in actively leaking cracks. Includes 10 injection ports and enough material for 10 ft.

4.5/5

Cures in wet/active leaks
Expands 20x to fill voids
10 ft coverage per kit
Flexible — moves with foundation

Check Price on Amazon

Drylok Extreme Masonry Waterproofer

$35 – $55 per gallon

The industry-standard interior basement waterproofer. Resists 15 PSI of hydrostatic pressure. Apply with brush or roller to bare concrete or masonry walls.

4.5/5

Resists 15 PSI water pressure
Covers ~75 sq ft per gallon
10-year warranty
Available in white and gray

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Quikrete Hydraulic Water-Stop Cement

$8 – $15

Fast-setting cement that stops active water flow in 3-5 minutes. Perfect for emergency leak repairs and sealing around pipe penetrations.

4/5

Sets in 3-5 minutes
Stops active water flow
Budget-friendly
No mixing required (just add water)

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Wayne CDU980E Sump Pump

$160 – $220

3/4 HP submersible sump pump for basements with recurring water issues. Handles up to 4,600 gallons per hour. Includes float switch and check valve.

4.5/5

3/4 HP motor
4,600 GPH capacity
Cast iron + stainless steel
Top-suction design (less clogging)

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Professional Basement Waterproofing Options

When DIY fixes aren't enough — or when the problem is systemic rather than a single leak — these professional solutions provide long-term waterproofing:

Interior Drain Tile System

Cost: $3,000 – $8,000 · A perforated drain pipe is installed around the perimeter of the basement floor (inside the foundation), connected to a sump pit with pump. Water that enters through walls or the cove joint is captured before it reaches the living space and pumped out. This is the most common professional solution and works for most basement water problems. Includes a 10-25 year transferable warranty from most contractors.

Sump Pump System

Cost: $1,000 – $3,000 (installed) · A sump pit is dug in the lowest point of the basement, and a submersible pump removes water that collects in the pit. Often paired with a drain tile system. For critical applications, install a battery backup pump ($200-500) to protect against power outages during storms — exactly when you need the pump most.

Exterior Waterproofing Membrane

Cost: $8,000 – $15,000 · The "gold standard" of basement waterproofing. The soil around the foundation is excavated down to the footing, a waterproof membrane (rubber or bituminous) is applied to the exterior wall, a drainage board is installed over the membrane, and new drain tile is placed at the footing. The most effective and longest-lasting solution, but also the most expensive and disruptive (requires heavy equipment and landscaping restoration).

Crack Injection (Professional)

Cost: $250 – $800 per crack · Professional injection of epoxy or polyurethane through the full wall thickness — from interior surface to exterior soil. Professionals use higher-pressure equipment than DIY kits and can guarantee full penetration. Most include a 10-year warranty on the specific crack. Recommended for cracks that have failed DIY repair or for cracks you can't easily access.

When to Call a Professional

Water entering from multiple locations simultaneously
Water seeping through the floor (high water table)
Cove joint leaking along more than one wall
Bowing or cracking walls (structural + water problem)
Previous DIY repairs have failed or leaks return
Mold covering more than 10 square feet
Finished basement with water damage behind walls
Planning to finish/remodel your basement (waterproof first)

How Much Does Basement Leak Repair Cost?

Costs range from a $10 tube of hydraulic cement to $15,000+ for full exterior waterproofing. Here's what to budget for each level of repair:

Basement Leak Repair Costs (2026)

Repair Type	DIY Cost	Professional Cost
Crack injection (per crack)	$20 – $80	$250 – $800
Waterproofing paint (per gallon)	$30 – $60	N/A
Sump pump installation	$200 – $600	$1,000 – $3,000
Interior French drain system	Not recommended	$3,000 – $8,000
Exterior waterproofing (full)	Not recommended	$8,000 – $15,000

Costs are national averages. Prices vary by region, depth of foundation, soil conditions, and access difficulty. Always get at least 3 quotes from licensed waterproofing contractors.

See detailed cost breakdown by waterproofing method

Basement Leak Repair vs Full Waterproofing

Not every basement leak needs full waterproofing. Here's how to decide whether a targeted repair is sufficient or if you need a comprehensive solution:

Targeted Repair Is Enough

✓ Single, identifiable leak source
✓ Leak only appears during heavy rain
✓ First-time leak (no history of water)
✓ Exterior drainage is the clear cause
✓ Unfinished basement (limited damage risk)

Full Waterproofing Needed

✗ Multiple leak sources or whole-wall seepage
✗ Water appears even without rain (high water table)
✗ Recurring leaks despite previous repairs
✗ Planning to finish/remodel the basement
✗ Selling the home (buyers expect warranty)

Pro Tip

Start cheap, escalate as needed. Always try the simplest fix first. Fix exterior drainage ($0-100), then seal visible cracks ($20-80), then apply waterproofing coating ($30-60). If leaks persist after all three, that's when you call a professional for a drain tile system. Most homeowners who follow this order solve their problem without ever needing professional waterproofing.

Prevention: How to Keep Your Basement Dry

60-70% of basement water problems are caused by poor surface drainage — rainwater directed toward the foundation instead of away from it. These preventive measures are cheap and highly effective:

Pro Tip

Clean gutters and extend downspouts. This is the #1 most impactful thing you can do. Clogged gutters overflow directly at the foundation. Short downspouts dump thousands of gallons of roof water right next to your basement walls. Clean gutters twice a year and extend all downspouts at least 4-6 feet from the house using extensions or underground drain pipe.

Pro Tip

Regrade soil to slope away from the foundation. The ground should drop at least 6 inches over the first 10 feet from your foundation walls. Over time, soil settles and can create negative grade (sloping toward the house). Add compacted fill dirt along the foundation perimeter every 2-3 years to maintain proper slope.

Pro Tip

Install window well covers and improve drainage. Clear polycarbonate covers keep rain out of window wells while allowing light in ($15-30 each). For existing wells, add 6 inches of clean gravel at the bottom for drainage. If your wells don't have drains connected to the footing drain, consider having them added ($200-400 per well).

Pro Tip

Run a dehumidifier year-round. Even without active leaks, basement humidity promotes mold, mildew, and musty odors. Keep humidity below 50% with a basement-rated dehumidifier (30-70 pint capacity). Models with built-in pumps and auto-drain hoses ($200-350) eliminate the need to empty the bucket manually. This is especially important in summer when warm, humid air condenses on cool basement surfaces.

Pro Tip

Inspect your sump pump every 3 months. If you have a sump pump, test it by pouring a bucket of water into the pit — it should activate and pump the water out within seconds. Clean the intake screen. Replace the backup battery annually. Sump pump failure during a storm is one of the most common causes of catastrophic basement flooding. Consider a Wi-Fi-connected water alarm ($20-40) that alerts your phone if water is detected.

Frequently Asked Questions

Written by

HomeRepairBase Editorial Team

Our team of home improvement experts and licensed contractors creates detailed repair guides, cost breakdowns, and troubleshooting tips to help homeowners tackle structural issues with confidence.

Basement Leak Repair: Find & Fix Leaks Permanently

How to Find Where Your Basement Is Leaking

Wall Cracks

Cove Joint (Floor-Wall Joint)

Window Wells

Pipe Penetrations

Floor Seepage

Pro Tip

Common Causes of Basement Leaks

Mold Warning

DIY Basement Leak Repair Methods

Repair Method by Leak Type

Find the leak source

Identify the repair method

Prepare and clean the repair area

Apply the repair

Fix exterior drainage (the root cause)

Best Basement Waterproofing Products

RadonSeal DIY Basement Crack Repair Kit

Drylok Extreme Masonry Waterproofer

Quikrete Hydraulic Water-Stop Cement

Wayne CDU980E Sump Pump

Professional Basement Waterproofing Options

Interior Drain Tile System

Sump Pump System

Exterior Waterproofing Membrane

Crack Injection (Professional)

When to Call a Professional

How Much Does Basement Leak Repair Cost?

Basement Leak Repair Costs (2026)

Basement Leak Repair vs Full Waterproofing

Targeted Repair Is Enough

Full Waterproofing Needed

Pro Tip

Prevention: How to Keep Your Basement Dry

Pro Tip

Pro Tip

Pro Tip

Pro Tip

Pro Tip

Related Guides

Foundation Crack Repair

Basement Water Leak Repair

Basement Leak Repair Cost

Frequently Asked Questions

HomeRepairBase Editorial Team