Water

Ingredient information

  • INCI names: AQUA / WATER
  • CAS number : 7732-18-5
  • Function: Solvent (Dissolves other substances)
  • The most used ingredient in cosmetics.
  • Usually appears as the first ingredient in cosmetic products (therefore makes up the majority of the product).
  • Organic-compatible (COSMOS Reference)


Description of water

Water is the most commonly used cosmetic ingredient. It is almost always listed first on the ingredient list because it is usually the ingredient with the highest concentration in the formula. The primary function of water in skin care formulas is as a solvent.


Despite claims about the skin’s need for hydration and claims about specific types of water, it turns out that a water concentration of just 10% in the outer layer of the skin is necessary for the softness and suppleness of this part of the epidermis, known as the stratum corneum. Studies that have compared the water content of dry skin to that of normal or oily skin have found no statistically significant difference in hydration levels between them.


Additionally, too much water can disrupt the essential substances in the outer layers of the skin that keep it intact, smooth, and healthy-looking. For example, remember how the skin on your fingers and toes “wrinkles” when you soak in the bathtub for too long.

INCI Beauty rating: Green

The ingredients in this dictionary are evaluated based on validated and peer-reviewed scientific research. Our main source is the French application INCI Beauty, which itself relies on European cosmetics regulations and various scientific reference bodies.


Regulations regarding usage constraints, authorized concentration levels and availability vary by country and region. This ingredient dictionary is for informational purpose only and is not meant to replace official sources. Its original content is in French, which is then translated into English. Although we strive to always provide you with correct and up-to-date information, if you have any doubts about an ingredient, we recommend that you consult the official sources of your country regarding cosmetic regulations.

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