Anode, Rust - exactly whats happening?

Some people have substantial rust issues with electric heating elements while others have minimal (me) to no issues at all. Since everything I know about water chemistry is from AJ's primer, I was wondering what in water specifically inhibits or causes the rusting for some.

Any ideas?

It's not so much what's in the water, as long as there are some mineral ions to conduct electrons. The corrosion is called galvanic corrosion, and occurs when a two metals come into contact with each other through an ionically conductive medium, typically water. The more active metal in the electrochemical series is corroded, and the less active is protected. If you have a stainless steel element in contact with a stainless kettle, no corrosion will occur. If as many of us do, you have a plain steel threaded section on your element, it will corrode instead of the stainless of the kettle. They can be protected by by putting a more active metal anode in the system. Typically magnesium or aluminum are used for anodes.

Your house water heater has a great big anode in it to protect the steel tank. The anode has to be in good electrical contact with the metal surface it is protecting, so they are bolted into place in keggles, and screw into place in water heaters.

Thanks for the answer, although I pretty much knew most of that. The question is why two people with the same pot & element will have varied levels of rust? Only thing that I could think of was the difference in the H20, which then got me thinking of what water mineral constituents helped or hurt the rust issue. Or is it possibly the cleaning after use that effects it?

Hard to know for sure that there are in fact two people with exactly the same element and pot that have varied levels of rusting. If there are, it may be due to how they clean, dry wand store their kettle. I doubt the mineral content of the water has any effect. So I guess I am taking the long way round to say I have no clue how to answer your question...

samc, I posed the same thought some time ago because I know that some of us have keggles with the camco 5500 watt element and have had issues with rust (me) and some haven't. I think the water chemistry does have something to do with it personally but I have no idea how.

BTW, one hunch that I had was that it may be due in part to how much dissolved oxygen there is in the water.