You usually need permission - and you also need to notify your rental insurance - since many policies do not cover damage from tank leakage, unless discussed and specifically in the policy. The permission is most important when your apartment is not on the ground floor.Now you’re really scaring me. I didn’t know you need approval from landlord. As far as damage goes if anything I’m responsible regardless. Any attorneys here or ppl who were in similar position. I’m in New York. Also laws are different in different states