Speaking of insurance - Homeowners insurance in the US does *not* cover flooding or most other water damage, INCLUDING landslides and damage to property caused by excess water on your property. This also included sump pump failures in basements, and any of your stuff a basement regardless of whether or not it is finished.
Your home office in the basement? Not covered.
Your family rec room below ground floor? Not covered.
Storing your outdoor gear? Bikes? Not covered.