First, diagnose
Grand Rapids homes on sloped west-side lots can take on water from a point well uphill of where it actually appears inside, so tracing the path matters more than treating the symptom.
The full scope
- Where water actually gets in, uphill or down
- Grading on sloped west-side lots
- Grand River water table versus surface runoff
- Wall or floor-joint origin
- A written record ahead of any estimate
Worth noting locally
Grand River water table has flooded Grand Rapids in 1904, 1905, 1947, 1948, and April 2013, when it crested at 21.85 feet -- proximity to the river is a standard question during any assessment.