Water Damage Legal Liability Insurance
  
See: Insurance. See Water Damage Clause. See: Water Damage Insurance.
The key idea is that water damage can come from many places, be a range of players' faults, and is really hard to permanently fix (mold is a thing). So most insurance companies specifically exclude many forms of water damage in their contracts, because they just don't want to be on the hook for an endless stream (literally) of problems.