William Thomson, better known as Lord Kelvin, invented an ingenious electrostatic generator known as a Kelvin water dropper.
Water does not exhibit an overall electric charge under normal circumstances, but contains many ions from salts dissolved in the liquid. Some of the ions are positively charged (cations) and others are negatively charged (anions), so that they typically balance each other out.
If a charged object is placed close to water, however, the ions in the water will separate into groups. Ions with an opposite charge will draw closer to the object. The object will repel ions with the same charge. This is the premise that the Kelvin water dropper is built upon.