The term hydrosol is derived from the Latin words hydro and sol, meaning "water solution." When plant material, such as the roots, barks, flowers, leaves, stems and seeds, is steam distilled to obtain an essential oil, certain chemical constituents of the plant first build up in the water.
Only after they reach their maximum solubility in water, do they start to collect in a separate layer on the surface of the water (the essential oil). Many of the water-soluble plant compounds and some of the oil-soluble compounds wind up in the distillation water.

During distillation, componentsof the plant are carried over by the steam and found in the waterleft when the steam condenses. Hydrosols should contain bothmicroscopic particles of essential oil as well as beneficial plantcompounds that are water-soluble and thus not present in essentialoils.

A hydrosol is the pure, distillate water that remains after essential oils are steam distilled from the original plant material. Hydrosols are usually clear and have the appearance and consistency of water.
Their aroma is generally, but not always, similar to that of the essential oil, but the aroma is usually much more subtle. Hydrosols contain small amounts of essential oil.
They also contain water-soluble components of the plant material that may not be present in the essential oil. The aroma, therefore, may differ somewhat from the plant's essential oil.
Some hydrosols do smell surprisingly different from the essential oil.

Generally, Hydrosolsare neutral to slightly acidic, and are a good match for the skin’snatural pH.
Hydrosols are less volatile than essential oils, so they can be used for a wide variety of purposes without being diluted.

Hydrosols can be used as: