The ingredient, explained
Aqua
Human studies examine repeated skin exposure to water.
Ingredient guide
What it is and what it does
Aqua is the cosmetic label name for water. It acts as a solvent, allowing compatible ingredients to dissolve into the liquid part of a formula.
About this ingredient: CosIng identity and functions via Open Beauty Facts ↗ · European Commission ingredient function definitions ↗
- Solvent
- Dissolves other ingredients in a formula.
Function definitions: European Commission ingredient function definitions (SCCNFP/0299/00, pages 16 to 20) ↗
Registry functions describe possible formulation roles, not results for a finished product. A dictionary entry is not an approval or a safety assessment.
A closer look
What the research shows
Human topical research
In 21 volunteers with experimentally irritated skin, repeated water exposure increased blood flow without a significant water-loss change. A separate 20-person study found increased water loss and pH after five days of forearm immersion in tap water.
What this does not tell us
These water-exposure experiments do not test water as an isolated active in a moisturiser. The skin condition and exposure schedule matter.
Sources for this summary. PubMed 9115917 ↗PubMed 25066831 ↗
Research review checked Oct 1, 2026
Bounded review of 24 local candidate records, selected relevant abstracts, and targeted exact-name primary-source searches. Not a systematic review.
Ingredient research is not proof that a product containing this ingredient works.
Read the 2 selected studies
Human topical research · n=21
Effect of water on experimentally irritated human skin. ↗
The British journal of dermatology · 1997
Human topical research · n=20
The effects of water exposure on biophysical properties of normal skin. ↗
Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI) · 2015
Follow the formula
Products containing this ingredient
From the Serenfold edit. Linked by the ingredient list, without an efficacy ranking.
Names and identifiers
Registry identity
Water
- INCI name on ingredient lists
- AQUA
- CAS registry number
- 7732-18-5
- EC number
- 231-791-2
Other recorded names (1)
- water
Sources for this ingredient record
- EU CosIng ingredient registry (via Open Beauty Facts taxonomy) ↗ · ODbL 1.0 (Open Beauty Facts database) · Recorded Aug 8, 2026
- European Commission ingredient function definitions ↗ · Recorded Sep 30, 2026