Yuck! We’ve tossed that idea around. :D(no pun intended) The plumber that came out said that it was not sewer water. There was no sign of water in the bathrooms (rugs on floor, ring in tub or sink, etc) or kitchen. As far as a backflow preventer, your guess is as good as mine. I wouldn’t even know where to look.
The neighbors houses are all fine. The plumber is stumped. Friends are stumped. We are stumped. The water remediators (sp?) said the water heater closet was the driest. The water heater closet and the laundry closet back up to one another. It was enough water to fill the washer, flood the laundry closet, dining room. wet the water heater closet, run into my master bedroom down the wall and outside the slab. I have no broken pipes in walls, slab, or elsewhere. The water meter doesn’t move when main line is off. I chalked it up as a freak thing when no more water showed up, but the second time, I’m more concerned because of course I don’t want it to happen again. I think next time I think I’ll ride out the hurricane just to see what’ll happen.
PS The washer and the water heater back up to one another. If the washer lines are open could it have backed up in the washer? If so, what could make that much force that the water would come out if the main water line is off? We’ve thought about installing a check valve. What is your take on them? The reason I keep going back to the water heater is that is only thing that I can think of that would hold that much water (48 gal).
Thanks for responding so quickly! 🙂