Welcome to the forum. The rod in my water heater is also the drain plug for winterizing. The do need to be replaced when the wear out. A new one is about 1/2" in dia. When it need to be replaced is roughly about 3/16" dia. The length of the rod is roughly about 6-8 inches long. Outside the water heater you will see a bolt near the bottom. That's where the water heater rod is. Now in saying that, It's been over a year that I did the same thing for the first time. I would fee more comfortable if someone else could confirm what I'm writting here. None the less, Welcome again and I hope this helps you out.