Pure water is a very poor conductor of electricity. This is because it contains very few ions, which are charged particles that can carry an electric current. However, when you add salts, acids, or bases to water, it becomes a much better conductor.

Here's why:

* Salts: When salts dissolve in water, they dissociate into their constituent ions. For example, table salt (NaCl) dissolves into sodium ions (Na+) and chloride ions (Cl-). These ions are free to move, allowing electricity to flow.

* Acids: Acids release hydrogen ions (H+) when dissolved in water. These ions can carry an electric current.

* Bases: Bases release hydroxide ions (OH-) when dissolved in water. These ions can also carry an electric current.

Therefore, the substances that allow electric current to pass through water are:

* Dissolved salts

* Acids

* Bases

It's important to note that even a small amount of impurities can significantly increase the conductivity of water. This is why it's dangerous to be near water during an electrical storm or to handle electrical appliances with wet hands.