Do you roughly know where the water pipe comes out of the house?
If yes, before tearing everything up, I would first try to find the pipe using the good old dowsing rod. No, this is not a joke. Simply bend two welding wires and then preferably slowly walk over the pipe at a 90-degree angle to where it is suspected outside. Hold the wires loosely in your hand; when you stand over the pipe, the wires should twist and cross each other. It’s best to search on Google for this.
We had a similar case with us. The old house that was supposed to be demolished still had the water connection, and no one knew where the shut-off valve was. So the supplier came, shut off the water in the area for 2 hours, and drained the pipe. Afterwards, they inserted a probe into the pipe, and someone always walked above with the search device looking for the probe. Eventually, we were at the shut-off valve. So, spade out, and after 20 cm of soil, it was there. They immediately measured it in and took off again.