Cleaning the drain plug/anode fitting threads on our water heater with a 3/4" tap - why so much corrosion?


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Last spring when I installed the anode in the water heater, it was hard to get the threads started because they are getting rusty. Why they are so rusty I don't know. The trailer has never seen salt and is only two years old.

Last week when I pulled the anode to winterize this is what I found. The threads look pretty bad.

Another angle

I ordered this tap set on amazon:

I didn't need the whole set, but why not when a single tap is not that much less.

I chased the threads and now this is how they look.

I found that the tap would bottom out before the tap got in far enough to really chase the threads. With my finger I could feel a ridge that was left at the inside of the fitting, probably so people wouldn't lose their plug or anode inside the tank.

You can see the position of the tap when it bottoms out.

I would like to know why the fitting is rusting this much. Maybe I should put more Teflon on the anode threads to reduce the contact between the anode and fitting? Or, would a more conductive interface reduce the corrosion of the threads? I'm assuming the difference in reduction potential is causing electrical flow between the water heater body and the anode, which is causing the rusting. So do you try to insulate the anode or provide the electrical potential a better path?
Hrm, you have me curious now. I've got a weekend off coming up. I might pull mine and have a look.

No idea why it would look that bad on yours, but that's grungy.
I think I'll stick an inspection camera in to take a look before I spray it out in the spring.
Checked mine out today. Nowhere near as gnarly as yours, but the anode looked like it was going to wear through right at the fitting and I didn't want it breaking off and rolling around in there, so I replaced it.

I'm wondering though if I used too much teflon tape on it and should it have an electrical connection to the tank.

--Edit-- Yep, quick google says it should. Guess I'll go check it with a meter and see if there's continuity between the tank and the rod.

--Edit Edit-- Maybe not:

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