Groundwater & Basement Water Intrusion in Dublin, OH

Because the water is moving below the surface rather than across it. Soil here is shallow over limestone; rain soaks through the thin cover, reaches the rock, and then runs along its surface downhill. That flow is invisible from above and can arrive at a basement wall from some distance away. It also explains why regrading a yard that already looks fine often changes nothing, and why the effective fix is usually below grade.

It can be, and it is a consequence of how the hole was dug. Excavating through rock and backfilling with granular material creates a zone around the foundation that is more permeable than everything around it. Water that reaches that zone collects in it rather than passing through. A footing drain that actually discharges is what prevents that from becoming pressure on the wall, so confirming the drain exists and works is worth doing.

One that works and one that works when the first does not. The single most common failure is a pump losing power during the storm that created the demand, and the second is a discharge line that has silted or frozen closed. A backup pump on independent power addresses the first; checking the discharge outlet twice a year addresses the second. Neither is expensive relative to what is typically finished in these basements.