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Your science teacher, your parents, and society in general has likely taught you that water is a good conductor of electricity, which is why “water + electricity” is a highly dangerous combination. What if I told you that water is actually one of the best insulators? In other words, water does not conduct electricity? Would you think I was talking a bit crazy?
Confused? Don’t worry… so was I when I first discovered this seemingly impossible fact. Let’s find out the secret behind this.
As we know, water is capable of dissolving a wide variety of different substances, which is why it is known as such a good solvent. In fact, water is called the “universal solvent”, because it is capable of dissolving more substances than any other liquid.
Does water conduct electricity?
Pure water: Pure water (distilled water) is the liquid that you get when water is boiled and steam is allowed to condense. The water that forms is devoid of any minerals and impurities. Pure water acts as an excellent insulator.
Plain water: Plain water is the water that you see at your house, tap water, rain water etc. Plain water contains different types of dissolved minerals, including calcium, magnesium, iron and sodium. Plain water, therefore, acts as an excellent conductor.
Why is pure water a good insulator and plain water a good conductor?
For electricity to travel through a liquid, a movement of charge must take place through the liquid. In tap water, rainwater and seawater, there are countless impurities, such as salt (Na+), calcium (Ca 2+), and magnesium (Mg2+) ions (source). Because these are charged, when they move through water, electricity is able to flow through the liquid. In distilled water, however, there are no impurities and therefore no ions. There are only neutral molecules, and these neutral molecules don’t have any charge. For that reason, distilled water is unable to conduct electricity.
However, distilled water is not something you come across that often, particularly in a bathtub, so you should always be careful about having electronics around large bodies of water, as that water is almost certainly plain. Pure water is very difficult to find, and even some distilled water will have some impurities, so in the long run, just assume that there are ions in everything!
However, as I stated at the top of this article, water itself does not conduct electricity. It is the impurities in plain water that conduct electricity.