No, pure water doesn’t conduct electricity; by itself, it is a poor conductor of electricity. However, water contains charged ions and impurities that make it a very good conductor of electricity.
We’re always told and taught that water conducts electricity. In fact, this is the primary reason why water + electricity is such bad news, as it can cause electric shocks to those who come in contact with the dangerous pair.
However, if you really think about it and dig into the depths of chemistry on this question, you’d see that pure water is actually not a good conductor of electricity. In other words, it doesn’t allow an electric current to pass through it.
Water: A universal solvent
Water dissolves a lot of stuff, which is why it is widely known as such a good solvent. In fact, water is often (mistakenly) referred to as the “universal solvent”, because it’s capable of dissolving more substances than any other liquid.
Most water that you encounter in your daily life has some amount of dissolved substances in it. It doesn’t matter whether the water comes from your kitchen faucet, your shower, swimming pool or anywhere else… you can safely assume that it contains a significant amount of dissolved substances, chemicals and minerals.
It’s highly unlikely that the water you have is absolutely pure, i.e., devoid of all salts, minerals and impurities.
Pure water doesn’t conduct electricity
For electricity to travel through a liquid, a movement of charge must occur throughout and across the liquid. Completely deionized water (in other words, absolutely ‘pure’ water) doesn’t have any ions. As a result, there is no flow of charge through water, so pure water doesn’t conduct electricity.
In distilled water, there are no impurities and thus no ions. There are only neutral molecules, and these neutral molecules lack a charge. For that reason, distilled water is also unable to conduct electricity.
Why is normal water a good conductor of electricity?
In tap water, rainwater and seawater, there are countless impurities, such as sodium (Na+), calcium (Ca2+), and magnesium (Mg2+) ions (source). Because these are charged, when they are present in water, electricity is able to flow through the liquid.
Water doesn’t need to have a large amount of impurities to act as a good conductor of electricity; even a small amount of ions can enable a source of water to conduct electric current.
In a nutshell, water is able to conduct electricity due to the dissolved ions and impurities within it.
If you place a battery into water with a positive and negative pole, the positive ions will be attracted to the negative pole and the negative ions will be attracted to the positive pole, thus creating a closed circuit.
Water is amphoteric in nature, meaning that it can act both as a base and an acid. It is a very good source of hydrogen, as electropositive elements reduce water to a hydrogen molecule, which is useful in redox reactions.
Water has the highest surface tension of all liquids, with the exception of mercury. This property of water arises through hydrogen bonding in water molecules.
Since the water that we use in our daily lives is bound to have impurities, it’s best to keep all electrical devices away so that they never come in contact with water.