They're responsible not only for their unit, but for the unit next door and any others that are damaged. Many renters don't know that renter's insurance exist. Others simply just never get around to buying the insurance or opt to take their chances that mishaps will swerve around them. But it does. Insurance firms said apartment fires and theft are the leading reasons tenants suffer losses.
Water problems caused by an overflowing tub or sink is another major problem.
San Francisco property owner Merrie Lightner once had two substantial overflow snafus in a single month. Typically, she said, a tenant falls asleep or becomes distracted while drawing a tub. If the distracted tenant does not have renter's insurance in such a case, the landlord's insurance carrier will pay for damage to the building and then may seek to recover the costs directly from the renter. Tenants in the lower apartment whose personal belongings are ruined also may get into the act. If the tenants don't have their own renter's insurance, they may have to sue the negligent tenant to recover their losses.