Recovering for damages from Watson explosion in Houston

My home owners insurance company only covered $500 for bathroom cleanup caused from my sewerage lines backing up when the underground concrete pipes collapsed due to the Watson explosion in Houston. This amount of $500 was well below my deductible of $3000. I paid a plumbing company $3300 to do a spot repair and fix the sewerage lines.

How do I recover the $3300 expense from Watson and / or my insurance company from the damage to my sewerage lines?