Of the thousands of exotic and instant-results ingredients touted in skin care, one has remained at the forefront for hundreds of years: plain and simple H2O. Skin dry and tired? Drink more water! It’s a nice idea — that something so readily available can also be a cure-all for skin. But it’s also a pretty broken one. Research hasn’t really backed up the idea that consuming water will make skin more hydrated.Here’s what we do know: Our skin needs hydration, which is why water is found in so many of our beauty products. “​Water typically acts as more than just a filler [in skin-care products],” says Raja Sivamani , MD, a dermatologist and assistant professor of clinical dermatology at UC Davis, who holds additional specialties in bioengineering and Ayurvedic medicine. “It contributes to the physical and chemical properties of a skin-care product.”Water does play an important role in helping the other active ingredients in a product perform. But what about specialty waters in skin care? Products that feature mineral waters from such geologically unique places as the Dead Sea or Icelandic glaciers, botanical waters including rose and artichoke, and, lately, waters that have been steeped in so-called healing energies, are all at the ready. Do these superwaters bring more purity to a product or more skin benefits than today’s typical water supply, or are they just gussied-up, more expensive versions of what's pouring out of your faucet?To help drill down on how these mineral, botanical, and ionic waters really affect skin, we consulted a coterie of complexion pros. Because while the whole fountain-of-youth thing has proved itself a bust (so far, at least), modern-day science and old-school geological wonders might prove once and for all that when it comes to skin care, water is the answer.