Florida Neighbor Using 12,000 Gallons Of Water From Our House

Hello everyone!

To be short, we have a next door neighbor to my grandmother's house who is an asshole. He's tried to manipulate the HoA and neighbors into having the city seize the house in order to buy it (she has dementia and lives with my parents so it's unoccupied), misrepresented himself as HoA and a member of Ameritek in a notarized letter to my parents (he's not on the board) and has threatened or tried to buy out the lawn care service I pay for (in order to, presumably, claim it's abandoned and that somehow plays into having it seized by the city I've been told).

As of today, I was told the property used 12,000 gallons of water in December. No one lives at the property, it has no pool, I've been there and nothing is running. He, however, has a pool whose dimensions would approximate that, and our other neighbor has told us when he visits (he occasionally assists with lawn work as we don't live there) a hose has been hooked up and dribbling water. We did not have a hose there.

We don't have cameras on the property, and while I think it's a logical observation if we contact the utilities that there's no way we used that, I'm not sure what the outcome would be (since it was clearly used) or how we could prove it's him.

Any thoughts?