Hydrodistillation is a very old technique that is said to have been used since ancient times by the Persians to make rose water. The etymology of the word attests to its traditional use: hydro is Greek for “water” and “distillation” comes from the Latin distillare, meaning “to drip.” Remains of stills dating from 3,500 B.C. were found in Iraq. In India, they date from the third millennium B.C. The Arabs were the ones to introduce hydrodistillation to Italy in the 12th century, whence it spread to Spain and, finally, France. It was not until the 16-17th centuries that essential oils were clearly identified and commonly used.

Hydrodistillation entails recovering essential oils from plants using water vapor. The natural aromatic raw material is placed in a still filled with water, which is then heated to boiling. The action of the heat causes the plant cells to burst and release the fragrant molecules that are carried away in the resulting steam. They pass through a condenser to be condensed by cooling. The water and essential oil separate by density difference in a decanter or essencier. The decanted water, called a hydrosol, is very fragrant. The hydrosol obtained from flowers is called floral water.