My tanks don't have indicators....you can tell be lifting one up or when the flame goes out. Mine last through a whole season of camping. I just changed out a tank from last year that I used, when it was empty. I even used it some to run my heater during the winter when I was out there working on the inside of the trailer. I don't know what size your trailer is though...mine is a 25RS. One thing to check is if your tanks are older they have a date stamp on them for re inspection.