Question: Is iron a better conductor than water?

Simone Sturniolo answered on 17 Jun 2013:

Yes. As surprising as it may sound, water is actually an insulator! Don’t go stick your hand in a bathtub while holding a powered on hair dryer though. You would probably die. In fact, only distilled water is a very good insulator, and your regular tap water is everything but distilled. See, the difference between iron and water is what ‘carries’ electricity in them. In iron, it’s electrons – small particles which are part of the iron atom (as well as any other atom, really). Iron is a metal: that means that its electrons are free to walk around wherever they want, and can carry electricity. In water, however, electrons are stuck to water molecules (H2O, that is, two atoms of hydrogen and one of oxygen, stuck together). So the only way for electricity to be carried is for there to be an “ion” – an atom or a molecule that has excess electrons from its normal quantity. You might say that electrons need to get a ride from an atom or molecule! But atoms are also much bigger and slower than electrons, so conductivity is worse. Additionally, in pure distilled water, there are almost no ions. Tap water is different though: there are lots of impurities of minerals or metals in it, that provide abundant ions. They come from the air, from the water tubes, or from the rocks the water flowed through before pouring out of the spring. That’s why normal water is a conductor and we need to be wary of it. Even still, water stays a much worse conductor than iron or copper. Makes sense, or we would use water tubes rather than electric wires, right?