Aqua

Aqua (deionized water) is purified water that has had its mineral ions removed through ion exchange processes, making it the most common cosmetic ingredient and universal solvent. Unlike tap water, deionized water is free from minerals, chlorine, and other impurities that could interfere with formulation stability, product efficacy, or cause unwanted reactions with active ingredients. Formulators choose deionized water as their base because it provides a clean, neutral medium that allows other ingredients to perform optimally without introducing contaminants that could affect color, odor, or preservation.