Just notice some water around the anode rod nut.

[Phog]

You were right. I sanded the paint off that water shutoff, and it sure looks like brass to me. I did not realize that brass could act like a dialectic between a galvanized pipe and a copper pipe!

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Glad to hear it. Technically it's not a dielectric (electrical insulator). It just is similar enough to both copper & to steel where the galvanic corrosion reaction is very slow with each. Think of it as a gentle intermediate transition between the two other metals. Whereas a dielectric union is a non-metal separation gap. Different mechanism, same effect.