Clean-up and a new tank could cost 25k.

Alternative means of purchase; HELOC if possibleNow one thing to consider here that I'd be happy to chat with you about in greater detail if you'd like is alternate ways to have your portion of the land income producing (if this is indeed a 'speculative investment scenario) - RV winter storage - ATV storage - POD storage Basically there are endless ways to have some income coming in IF this property isn't already producing for you and isn't tillable, and I can help you figure that out if you'd like.

Past tenants have used it for storage of art supplies, or to keep reptiles and whiffle board table. 

I've been managing for 11 years and currently have about 400 rentals and 350 storage units.

This can be particularly true for special use assets like holding tanks, railspurs, cranes, fixtures, etc.

The house is on well/septic and the storage tank runs out of water every day.

It is a single-family w/ a 2x1 and a duplex with a 2 x1 unit and an efficiency unit with 2 storage areas that can be turned into a 2x1.

That should be enough to cover the cost of moving their stuff to storage, cleaning and eviction.  

I wanted to buy a storage unit last year, so I just called every storage facility I could find to see if anyone was interested in selling.

The self-storage and industrial buildings has been what is attracting me the most, though I am hesitant to jump in on any deals.