I second what Steve Hull posted.. After reading about propane sinking into the nearest hole,
I decided to move all my plumbing propane out to the garage.. (No basement)..
After a few years out there, there isn't much rust on the bottles..
My basement is a bit damp, and has radon gas, but it's propane free!
Thinking about sump pumps right now.. Wondering if they all have explosive-poof switches?
I remember a time about 35 years ago, when I used a standard micro switch to make
my own float switch, to power a submersible pump..
(The basement was flooding at 2AM and I needed sleep)..
Thank the PTB there wasn't a propane leak! Because I used that hack,
until the pump died about 5 years later..