Most wet basements aren't foundation failures — they're water management failures. Keeping water away from the foundation is far cheaper than dealing with it once it's inside.
Start with grading and gutters
The ground should slope away from the house, and downspouts should discharge well away from the foundation. These two cheap fixes solve a large share of basement moisture problems before any digging is needed.
Weeping tile
Weeping tile (perforated drainage pipe) runs around the foundation footing to collect groundwater and carry it to a sump or storm connection, relieving pressure against the walls. Older homes may have clay tile that's collapsed or clogged with roots and silt.
Interior vs exterior solutions
When drainage fails, an interior perimeter drain with a sump pump is the most common fix and avoids excavation. Exterior excavation to replace weeping tile and re-waterproof the wall is the most thorough — and most expensive — option, used for serious or recurring problems.