Only way water is getting into your bays from overflows would be inside the coach and leaking down. The tanks are outside the bays and should bee water tight. Take it to the factory and have them fix it. If you can't then as suggested by another poster, the vaseline method of finding the leaks. Check the seal on top under the hinges as you said you hadn't been driving it which would sling water up from the road. The factory put some rubber strips or something behind the seals on two rear compartments on ours. We were getting road dirt in those two, that were for hoses and such not luggage 12-14 years ago.