First you need to check your water meter and see if there is movement on the gauge meter. Then you need to turn off the hot water off. Re check the meter for movement. If the meter stops then you might have a hot water leak in the location you found. Without proper equipment it is hard to locate water leaks. You wouldn't want to break up the flooring and find that the water leak is another 5' from that location. What you need to do is call the PRO's and let them locate the leak. Call around and get prices. Be sure you are comfortable with the information they give you and also the prices. They might even suggest to reroute the water line in the ceiling. Most slab piping has manifolds in a wall near another location (bathroom, laundry, etc...) They can cut off the leaking line from the manifold and open the wall and reroute to the kitchen overhead in the ceiling. It's better than breaking the foundation flooring. It's not going to be cheap, so get those estimates and compare.