Correct. Do your have family, mom / dad / grandparents/ uncles / aunts. Is there a range they lived to? Are there “known” issues for your family, heart disease. Are you living a healthy lifestyle. Take all this info, and you’ll get an approximate range . For me, I expect 80 -85. I could go sooner, or go longer. But I doubt I’ll make it to 90.

Is the water heater still under warranty? The manufacturer sent me the parts. I hired a plumber to make sure they got installed properly

Is the water heater still under warranty. If so, the manufacturer could send the parts. I used a plumber to make sure the parts got installed properly.

Run a snake down the drain, perhaps a sock has stopped it up.