Help – My home has the sound of water running at a high rate. Was told is at a rate of 300 gallons an hour even when toilets, sinks, appliances, are not in use.

Starting to notice floors arching slightly although foundation was recently redone a couple of months ago. One plumber suggested repiping ENTIRE property( can’t go that route). Another plumber just cut a piece of sheet rock and said IDK 🤷‍♂️ and left. It’s pier and beam. What can it be?? How do I fix it? Has anyone filed a successful Homeowners Insurance claim for a similar situation?