Water doesn’t need to have a large amount of impurities to act as a good conductor of … But not all impurities can do so, only those that can contribute ions, such as salt.

Tap water is such a solution.

Deionised water, however, as well as nearly all types of purified water products, is not a good conductor because of its lack of salts. Ordinary distilled water in equilibrium with carbon dioxide of the air has a conductivity of about 10 x 10 -6 W -1 *m -1 (20 dS/m). Tap water, which hasn’t been purified, is very conductive because it contains a lot of dissolved salts. In tap water, rainwater and seawater, there are countless impurities, such as sodium (Na+), calcium (Ca2+), and magnesium (Mg2+) ions (source). Why is normal water a good conductor of electricity? That is why you MUST NOT touch electrical outlets or switches with wet hands.

Because the electrical current is transported by the ions in solution, the …

Because these are charged, when they are present in water, electricity is able to flow through the liquid.

Water conductivity Pure water is not a good conductor of electricity. Most water we come into contact with, such as tap water or not completely distilled bottle water, contain impurities that turn water into a conductor.