Hi, Water is beginning to leak from somewhere when we turn the shower on. If we turn the water on just to fill the tub, there is no leaking; only when we turn the shower on. I see no leaking from the faucet behind the wall to about a foot down inside the wall. The grout is all new on the walls and around tub. The leak starts immediately. Where could the water be coming from? If it is a major job, will homeowner's insurance cover it? THANKS! :)