INCI name
Aqua
Also listed as: Water, Eau
Aqua is water. On an ingredient list it is almost always first, because water is usually the largest part of a cream, lotion or cleanser.
Cosmetic chemists use purified water, not tap water, so that minerals and microbes do not interfere with the formula. The INCI name is Aqua in many countries and Water on some US labels. They refer to the same thing.
Water itself is not a common allergen. Problems with a watery product usually come from the preservatives or fragrance that keep or scent that water, not from the water.