water pipes in foundation?

If the pipes are in the slab, and the slab is sitting on the ground and not elevated, then you should not need to worry about them with the temps you describe. In the northern climates it can freeze down several feet deep, so that is a different story. But if it was me I would let the faucets drip anyway. It is cheaper to pay a few dollars in water for a couple of days, than thousands in repair bills

The water pipes, if buried in the concrete slab on grade or under the slab in the fill under the slab, will not freeze if you keep the house temperatures in the normal range and will not freeze under the slab unless it is exceptionally cold for an extended period of time and your house temperature is not maintained. Although the ground may freeze to a depth greater than the depth (thickness) of the slab, houses are to have a perimeter foundation walls, or turned down edges, that are deeper than the deepest anticipated frost, freezing, depth in your area.

Pipes may very well freeze if the temperature at the pipe gets into the 20's over night. If you have pipes in exterior walls and your insulation in the wall is not adequate or missing in the pipe chase the pipes are more likely to freeze. A little water running in the lines through the exterior walls would be inexpensive attempt to avoid freezing. Unless you have frost proof outside faucets, which would generate a minimal concern even without supplemental wrapping, I would be most concerned with the standard faucets even with a wrapping. Insulate / protect the exterior faucets as good as possible. You may want to check to see if the outside faucets may have an inside valve where they can be shut off. The open the exterior faucet and drain them.

Your correct about the under slab pipes. She's correct, but for a different reason, to leave the water running to avoid freezing. You're both correct, celebrate it, it doesn't happen often.

This depends on the construction of your house. If your house is built on a slab then water pipes are in the ground buried underneath the concrete slab and should be safe from freezing. If your house has a basement or crawl space you may have pipes running through this area and these are prone to freezing if the area is not heated or insulated well.

Sounds like it is ground water seeping in through the foundation around the pipe. I bet there is a small crack around the pipe. You could try packing the crack with hydraulic cement and see what that does. If it were water from the pipe it would be shooting across the room like a garden hose.

I agree with Chuck....