We have a claim under a BOP 00 03 01/06. It appears that a prior owner built an add-on over an underground cistern that is no longer used to service the home. The cistern has now collapsed creating a 12 x 12 opening that extends outside of the foundation wall.
The question is would the abandoned underground cistern be considered covered property under the BOP? Would it be considered a fixture even though it is not connected to the structure in any way?

Kentucky Subscriber
As found in the headnotes of Matthew vs. City Ice and Fuel Co., Court of Appeals, Fourth Appellate District, Gallia County, Ohio, August 17, 1982, No. 81 CA 6, in real property law, a cistern is deemed a plumbing fixture:

Fixtures & Improvements, Fixture Characteristics
Given the nature of a cistern and related water system and its attachment to real estate, such items are fixtures to the real estate and not personal property.

However, since it is no longer used as a plumbing fixture, it is our opinion that an abandoned underground cistern meets the common definition of a structure, which Merriam Webster defines in part:
Structure
1: the action of building : construction
2a: something (such as a building) that is constructed
2b: something arranged in a definite pattern of organization

You do not say what caused the cistern to collapse, but you might want to pay particular attention to the earth movement and other exclusions in the policy.