A few appliances running would spike a water bill around quite a bit. 

Does anyone have any costs or any idea what it would cost to remove a 500 Sq Ft in-Ground Vinyl Swimming Pool with a surrounding Concrete Sidewalk/Walkway? 

A lot of pools were built in an era when enclosing the yard was thought to be enough, but it never is.  

Your rental dwelling policy will cover if you have water damage coverage.

Unfortunately, this led to a fairly substantial amount of water leaking to the unit below and causing at least some visible wall/ceiling damage.My tenant caused the flooding (he has admitted in writing that this was the case).

yes, typically a sign of hard water, may need to add a water softening system. 

The cost of public water and public sewer bills have increased drastically.

If the y want to stay I would have a convo with them re: pool, landscaping etc...Good Luck

Value added by turning a 3 bedroom, 2.5 bathroom into a 4 bedroom, 2.5 bathroom This includes new roof, 2 new HVAC systems for split units, water heater, updating electrical/removing nob & tube wiring, plumbing updates, 17+ brand new double paned windows throughout, leveling out the flooring and adding hardwood throughout the entire property, replacing all drywall on walls & ceilings with over 100 new sheets, gutted both bathrooms to update tiles/vanities/ tubs and showers with 2x1 tile throughout for a modern feel.

On the day of final walk-through before closing, I noticed a small water puddle around the cove joint in the basement.