My in-laws in TN have a neighbor who DIY'd their own septic with an IBC tote (big plastic cube for shipping liquids). I doubt it has multiple chambers for settling or proper volume to ensure solid settle and breakdown before flowing out into the leach field. Probably doesn't even have proper setup for the leach field so water and sewage gases (methane) is likely just dumping out an overflow pipe into the ground.
It its amazing what people do...
Yeah, you can imagine the stories I get to hear every day....

