Get a new one. 20 years is a long life for a water heater. It's amazing how much more efficient they are today.
x2. Those are cheap as far as home maintenance/repair items go.
I have so much to do around the house but really don't care to do any of it. Next is to tear out walls in the basement and get to bare cinder block to get rid of the mold and damp from the hurricane. Need to repair my storage building too. Those idiots installed a chimney in there for a wood stove and did just the WORST job possible.