If it was coming from inside the house, that really was loud. On the other hand, if it’s open ground around there, sound can be distorted as if it originated from another location on the property. I wonder still about 55-gallon drums like they use on construction sites. They are sealed/unsealed with mallets, and if you roll one into the back of a truck, they make a lot of banging noise. That’s especially if you are trying to do it alone and it contains something—they are heavy anyway but with, perhaps, another 120 pounds in one, they’re heavy and unwieldy. Usually two people handle them. If one, you’d need a ramp to roll it up and if it’s on its side—easy to conceal and maneuver, it’s bound to roll and hit the truck bed. Banging sounds ensue, of course. I’m not saying this is what was going on but I’ve observed this kind of thing many times. Dumping a drum into water is not so rare. No idea if any of these other things are there but maybe: cistern, large freezer, fuel-oil storage tank, porta-potty (NO!), a jacuzzi tub, under a tub, even a water-well pressure tank. Those would be large for a large house and are inside the basement often if there’s a basement. Definitely big enough to hold a person. No idea if those houses have wells. I’m sure all of this has been considered but this is all I know to do to maybe help.
