If you have a leaking pipe underneath your foundation, it is either a water or sewer line. Repairing the damaged line is not that hard, however locating and gaining access to it is a different matter. Once you locate the general area of the leak, you will have to cut and chisel your way through the concrete to repair the pipe. There are several signs that point to a slab leak. The first is the presence of water or damp spots on your floor. Leaking hot water lines can create warm spots on your floor. Walking around inside your home barefoot will expose the location of the leaking hot water line. The second give away alerting that your water lines are leaking is the sound of rushing water underneath your floor.