HomeGuide puts the cost to repair a foundation leak at $250 – $15,000 nationally (source). The low end is sealing a single leaking crack. A full interior drain tile system with a new sump pump sits much higher. Where your job falls depends on a few things.
Feet of wall, not square feet of floor
People often ask about a "2,000 sq ft basement," but waterproofing is priced by the length of wall treated, not the floor area. An interior drain tile system runs along the walls, so a long, narrow basement can cost more than a square one with the same floor area. And if water only comes in on one side, sometimes only that wall needs work.
What changes the price
- Interior or exterior. Interior drain tile is usually the less expensive way to deal with water from walls and floor. Exterior waterproofing means digging to the footing and costs more.
- Sump pit and pump. A new pit, a quality pump and a battery backup add to the total. Reusing a good existing pit lowers it.
- Wall membrane. Block walls usually get a dimple membrane so water seeping through the block reaches the drain.
- Finished basements. Drywall, flooring and built-ins along the walls have to come out and go back.
- Cracks and walls. Leaking cracks or bowing walls are extra.
Why it costs what it does
Interior drain tile means cutting and removing concrete along every treated wall, digging to the footing, hauling out debris, setting pipe and stone, installing a pit and pump, and pouring new concrete. It is heavy, dusty labor. More in why basement waterproofing is expensive.
Cheaper things to try first
Before paying for a system, check the gutters, extend downspouts well away from the house and fix grading that slopes toward the foundation. These often help, and they cost little. See can I waterproof my basement myself.
How the systems work: basement waterproofing.