Water: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: June 30, 2025
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We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Water?

Water is the clear odorless liquid that makes up most of the planet and our bodies. In cosmetics you may see it labeled as Aqua, Purified Water, Distilled Water, Deionized Water, Micromatrix Fractile AN or Onsen-Sui in Japanese products. No matter the name, its chemical makeup is H2O, two hydrogen atoms bonded to one oxygen atom. Companies usually start with municipal or spring water then run it through filtration, distillation or deionization to remove minerals, microbes and other impurities. This extra processing gives a stable, predictable base that will not interfere with other ingredients.

Water has been part of beauty routines for centuries, from ancient bath rituals to the first cold creams mixed with rose water. When modern cosmetics manufacturing took off in the early 1900s, purified water became the standard base for creams, lotions and toners because it blended well with both oils and water-soluble actives. Today it shows up in nearly every category you can think of: cleansers, moisturizers, serums, sheet masks, peels, hair conditioners, styling gels and even toothpastes.

Water’s Cosmetic Benefits/Uses

Below are the main roles water plays when added to a formula.

  • Antiplaque – In oral care products like mouthwashes and tooth gels, purified water carries antiplaque agents evenly around the mouth helping them stick to teeth and gums so they can limit plaque formation
  • Skin Conditioning – Water hydrates the outer layer of skin on contact making it softer and more flexible. In leave-on products it also helps dissolve humectants such as glycerin that then draw extra moisture into the skin
  • Solvent – Most actives, thickeners and preservatives need a liquid medium to disperse properly. Water dissolves or suspends these ingredients, creates an even texture and lets the formula spread smoothly on skin or hair

Who Can Use Water

Because pure water is neutral and non comedogenic it suits every skin type including oily, dry, sensitive and mature skin. It simply helps carry other ingredients without leaving residue or clogging pores so there are no type specific restrictions.

Water is a mineral based substance that contains no animal derivatives so it is fully acceptable for vegans and vegetarians.

Products that rely on purified water are generally considered safe for women who are pregnant or breastfeeding. This is not medical advice and anyone expecting or nursing should still run any skin care product past a doctor to be on the safe side.

Water does not cause photosensitivity and will not make skin more prone to sunburn. There are no known incompatibilities with common skin treatments such as retinoids or acids.

Potential Side Effects/Adverse Reactions

Individual reactions to topical water can vary. The points below describe potential side effects although they are rare and most users will not experience them when products are manufactured and stored correctly.

  • Skin irritation from residual contaminants – if purification fails and microbes or cleaning agents remain the formula can provoke redness or stinging
  • Dry feel after evaporation – applying plain water on its own and letting it air dry can temporarily pull moisture from the skin surface leaving it tight
  • Exacerbation of hard water sensitivity – rinsing with mineral heavy tap water may contribute to itching or flaking in very sensitive individuals although purified cosmetic water normally avoids this issue
  • Microbial growth inside product – if a finished product is improperly preserved water provides a medium where bacteria or mold can multiply leading to odor discoloration or infection

If any discomfort rash or other negative effect occurs stop using the product and seek advice from a healthcare professional

Comedogenic Rating

Rating: 0 / 5. Water is a simple two atom molecule that leaves no residue on skin and evaporates quickly so it cannot block pores or trap oil. Its role is mainly to dissolve and transport other ingredients which makes it inherently non clogging.

This means water is fully suitable for people who are prone to acne or breakouts.

The only caveat is that if a finished product is poorly preserved any microbial growth in the water phase could irritate already inflamed skin, but this issue relates to preservation not the water itself.

Summary

Water acts as a solvent, skin conditioner and carrier for antiplaque agents. By dissolving actives and creating a uniform base it lets creams spread easily, helps humectants draw in moisture and distributes oral care ingredients around teeth and gums.

Because of its versatility and low cost it is the most popular cosmetic ingredient on the planet showing up in everything from cleansers and moisturizers to hair gels and toothpastes.

When purified correctly water is considered extremely safe for all skin types including sensitive and acne prone skin. As with any new product though it is wise to do a quick patch test to ensure the complete formula agrees with your skin.

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