Aqua/Water/Eau (also known simply as water) is the most commonly used cosmetic ingredient. Aqua/Water/Eau in skin care products is almost always listed first on the ingredient label because it is usually the ingredient with the highest concentration in the formula. Water's primary function in skin care formulas is as a solvent. https://www.paulaschoice.com/ingredient-dictionary/ingredient-aqua-water-eau.html?q=aqua&fdid=ingredients