If our neighbor left their hose on and our basement flooded, if they are only renting who is responsible for damages - the tenant or the landlord?
A definitive answer has to take cognizance of all the facts--e..g did the hose stay on because the valve on it was defective, which would tend to be the landlord's responsibility? However, that said, from what you write, it would seem that normally it would be the neighbor who is liable, or financially responsible. The neighor is the one who would typically be at fault in this scenario; he or she either intentionally left the hose on or negligently (carelessly) did so. The landlord--or any property owner--is not usually liable just because something occurs on his or her property; rather, liability hinges on some bad act, some careless act, or, at a minimum, a failure to exercise reasonable care to avoid problems. If the landlord did nothing wrong and the neighbor left the hose on, it should be the neighbor's liability.