Check who owns the tank. When we bought our place 3 years ago we were told the 500 gallon tank that was buried out back was leased. When we didn't respond quick enough after closing, took us a couple of months to move, they came out and disconnected it from the house without leaving a note or anything. We move in and wonder why the demand hot water didn't work. Luckily the heater displayed a code that I could look up online and it said no gas. Called the LP company to tell them I had a problem and they said they knew what the problem was and would be out in a couple hours to fix it. The fellow admitted when he came out that he had just disconnected the tank the week before since I hadn't paid the yearly lease bill.
We use LP for backup heat to the heat pump, highly recommended in this climate, hot water and fireplace. The lease kills the price but it is a good back up. We fill up once a year in the Summer and it was $2.40/gallon last month. Yearly lease is $164. They tried to charge us another $91 minimum charge when I didn't call them soon enough for a summer fill but dropped that when I called and complained. We use 100-140 gallons/year and they said minimum was suppose to be one tank full but if I put it on automatic yearly refill they would wave that. This was the first we even heard of a minimum usage fee. They offered to sell me the tank when we first contact them, don't remember what they wanted but it might have paid off in the long run since we could shop for cheaper supplier, but now they are respresponsiblele if there is a leak.