I second State Farm. When I started my tank 2 years ago, potential liability/damage was top of mind since I live in a multi-unit building and I was trying to get reassurance. That said, a few companies blanketed their responses with the "yes of course we cover that", but when pushed they couldn't provide clear language in their coverage contract... and one even reversed their statement after I pressed them.
Just be sure to ask for clear language that would support such claims. I was content with State Farm's description of what they covered after going back and forth with them a bit.