That looks awful, the full extent of the damage will take a lot of time.
Homes, and their plumbing drain systems will have taken a lot of abuse that they were never intend for.
If on a slab foundation, it could mean concrete removal to make repairs....
I know, I use to be a plumbing contractor before I went to building aircraft.
Septic systems (drain fields) might be rendered no good now, won't perk.
You will have to dig up all the earth in its field and replace.
That soil can not be just dumped anywhere, depending on local codes, it can be listed under hazardous waste, and extremely expensive affair to treat.
Anything having been flooded, all systems, pneumatic, electrical, etc, are now suspect and will have to come with a disclaimer in any future title changes.
I am afraid the cost of this can go on for decades.
Be well, you have your life, that is paramount!
NOTE: Be careful of "cheap" cars, tools, appliances etc, in the future on Ebay, CL, etc.
Often it is bought in wholesale lots, and made pretty, moved far away from suspect, and dumped where folk don't put two and two together....
Until its too late.