However, in the old days of building houses, builders often mistook damp-proofing with waterproofing. Waterproofing and damp-proofing may be related, but they are totally different in their scoops.
For years, foundations were merely damp-proofed, not waterproofed. As it was, damp-proofed foundations and basements were only able to stop water vapor. It was unable to bridge over the cracks that can develop in the foundation over the years.
With time, water in the ground can develop its own hydrostatic pressure and can push through foundations that are only damp-proofed. After some time, damp-proofing materials may also become brittle and increase the risk of water seepage.