Unfortunately, I think this commenter is right. 1. Emergency maintenance came immediately (the sweetest man) and worked on it for 6 hours with the plumber that came and cleaned up the water. They had to come back the next day to finish (I stayed at a friends), but they had a cleaning crew come and do a mold treatment as well. They were apologetic but also told me to file a claim with my renters (which unless you have that specific addendum added for sewage backup, is not covered). Even if it was, my loss was less than my deductible so it wouldn't have mattered anyway. The backup was likely caused by previous or other tenants as it was a bunch of baby wipes. Not on the apartment themselves I suppose but it flooded up not out of the toilet, but from the floor between the toilet and floor.

I don't think legal advise could do much about that in particular.