[bcj]

Unless concrete is properly finished/sealed, and that finish/seal is maintained, water will seep in eventually. One failure I've heard of is water seeping into the edge of a concrete balcony causing the embedded rebar to rust.

In the building I lived in there was water ingress at the seam between the wall and the windows. Also leaking from a water feature down into the parkade after the membrane wore out. Neither of these failures was the "fault" of the concrete per se, but they happened in a concrete building nonetheless.