You just bought a bottle of lotion and decide to read the label. You note the first ingredient: Aqua.

What Is that, you ask? Isn’t that just water? Is “Aqua” water different from “Water” water?

Water is used in the formulation of virtually every type of cosmetic and personal care product from lotions, creams, deodorants, and makeup to oral hygiene products, shampoos, hair conditioners, and shaving products. Primarily used as a solvent to dissolve many of the product’s ingredients, such as conditioning agents and cleansing agents, water also forms emulsions in which the oil and water components of the product are combined to form creams and lotions.

But, significance differences exist in where that water – or aqua – as an ingredient comes from. For example, tap water from a city water supply is often filled with a small amount of metal and mineral ions. This usually may have no effect on a cosmetic formula but can affect some formulations. For DIY formulators, tap water is probably not the best option.

Distilled water is obtained through boiling and condensing. With a few exceptions (e.g., some alcohols), the process removes all traces of contaminants. However, distilled water will typically have a lower pH (4.5 – 5.0), which may or may not affect a formulation.

While tap water is usually filled with sodium, calcium, and magnesium plus metal from the pipes, such as iron and copper, deionized/deminerized water is obtained via an ion exchange column. Ionized water goes in, deionized water comes out. This process does not remove organic contaminants, viruses, or bacteria.

Finally, ultra-pure water is obtained through a bit more complicated procedure: The water is first demineralized then sent through an electrodeionization process. Ultra-pure water is best suited for electronics and pharmaceuticals. For cosmetics and personal care products, this is an over-kill.

So why “Aqua”? Why does a manufacturer use the Latin form of the word, rather than the more recognizable term “water”? Perhaps it is simply a more glamorous term or, more likely, in line with the polysyllabic and unrecognizable ingredients in the product, like tetramethylhydroxypiperidinol? Who wants just plain old common “Water” when you can have “Aqua” instead! Boring!

In the U.S., The United States Food and Drug Administration (FDA) summarizes the Fair Packaging and Labeling Act (FPLA): If a cosmetic product is marketed on a retail basis to consumers—such as in stores, online, or “person to person”—the ingredients must be listed by their common or usual names, generally in descending order of predominance. For such consumer products, the FPLA actually prohibits the use of the word “aqua” on its own. Cosmetic companies sometimes ask FDA about identifying botanicals only by their Latin names … such as “Aqua” … instead of “Water”.

Under the FPLA, however, ingredients must be listed by their “common or usual names,” and FDA does not accept these alternatives as substitutes. (This does not apply to products distributed only as free samples, for professional use, or for institutional use, such as at schools, hospitals, or the workplace.)

Is “Aqua” water different from “Water” water? Regardless of what it is called, water remains a critical ingredient in cosmetic and personal care products.