We have had a buried propane tank for over 10 years. The underground tanks are made differently than the above-ground tanks. In Nassau County, you have to have an approved contractor put it in and the Fire Marshal has to approve the design of the installation and inspect the installation before you can use it (and the propane companies first check with the Fire Marshal's office before they will make any deliveries to you). In our case, the supplier that was hired by our generator contractor (the reason we got it) gave us the option of owning or leasing. We went with owning because of the flexibility it gave us to change suppliers later if we wanted to do so.
That flexibility was helpful after Superstorm Sandy, when I fired our supplier (Paraco) and hired a different one (Petro). The day after the storm, with our generator running at the beginning of what would be a 15-day power outage, I calculated my needs, called Paraco, and scheduled a delivery for three days' hence. "Fine" they said. "No problem." In the interim, they took a million calls from people and went into crisis mode. They simply failed to show up on the appointed day. When I called them, they said that unless I lied (like everyone else was doing) and said that the tank was empty and the generator had quit, they wouldn't even put me on the schedule. I wasn't willing to lie. Part of this was a problem of their own creation because they were disinclined before the storm to top off people who had more than half a tank, as I did. So I called Petro, and found out that they had brought in trucks from out of the area to help with the demand, and that their coordinator had called all her generator customers a week before the storm and offered to top them up, an offer most of them had taken her up on. Smart company. So now they weren't dealing with a mass of people who all needed fills during a crisis. She was happy to take on new customers, while the other vendors were struggling to handle their existing customers. So I fired Paraco and hired Petro. She set me up for an inspection and certification of my tank (some kind of regulator test or something that they had to do before delivering to me) that day, and had a truck there the next morning. We were under 5 percent on the tank when the truck arrived, which is well below what I had understood to be required to generate enough pressure to run the generator, but we still had a running generator when Petro arrived to fill us. It all worked out. Had we not owned our tank, we would have been screwed. (As an aside, I later found out from my electrician/contractor that he had enough pull at Paraco to get his customers to the head of the line if they called him to complain, and he was sorry he hadn't checked with me. We were the only ones of his many customers that had had issues getting gas. That actually made me even angrier at Paraco: while they were telling me that they "had to serve the hospitals and nursing homes first", which is totally understandable, they were actually playing politics with who got gas and who didn't. So we are never ever going back to them.)