[johnsjmc]

Looking at the supply pipe it looks like a continuous piece of soft copper pipe. commonly direct buried around here and should last for decades. In clay or cement life can be reduced by galvanic corrosion but still long lasting stuff. The hole through the floor where it enters is the likely route of water entry. I suspect you have a high water table Has it been raining a lot. Is there still snow melting way up there in little canada? LOL.
Even with no signs of weeping tiles or a French drain a house might have tiles laid under the floor connecting to the building sewer. They could have been added years ago too. I just had a basement flood in a 1890 house. Turns out weepers were under the floor and te main sewer was choked with roots. As other said vacuum up the water and see where it comes back in . call a plumber and if it appears to be an expensive fix call the real estate agent because the previous owner probably had similar problems.