Jess Altieri picks up the glass to the right of her plate and gives it a swirl, holding the base as to not change the temperature of the liquid she’s about to sip. After tilting it back and giving it a whiff, she takes her first taste, making sure it hits all the flavor points on her tongue before finally swallowing. Then, she sets her water back down.

As one of two water sommeliers in the country, Altieri is attuned to the minute taste differences that would be indistinguishable to the untrained tongue. She can taste if a water is high in minerals, like calcium (which is milky and smooth, though too much calcium makes it taste chalky), or electrolytes (slightly salty). She knows if what she’s drinking is Vichy or Smartwater without catching a glimpse of the bottle. And she knows what foods pair best with each brand.

But before she was swirling water in her glass, Altieri focused on wine. She was—and still is—a certified wine sommelier and California wine appellation specialist. “As a wine somm, I would travel the world, going to Italy, Austria, France, New Zealand, and Hong Kong,” she says. “I realized that at 90 percent of the dinners and wine tastings I attended, water was offered and served before the wine and dinner, yet the serving staff knew very little about the water or how it was paired with the meal being served.” She started doing a little digging to see if water tasting was even a Thing. It turned out, it totally was.

“My research led me to the one and only place to become a certified water sommelier: the Doemens Academy, located in the small down of Gräfelfing, Germany,” she says. Altieri enrolled and spent three weeks in Germany completing the 80 hours of certification work. For her, tasting the difference between various waters was an acquired skill, not something she was “born with.” So the training was well worth it. She left a budding connoisseur—and very well hydrated.

“You wouldn’t drink a bottle of Smartwater with a five course Michelin dinner, just as you wouldn’t drink a $100 bottle of Svalbardi after a cardio workout.” —Jess Altieri, water sommelier

Now, she creates and leads water workshops with different themes, often for major beverage companies who want tips on what makes a good-quality water, often to help inform major investments. “One of my most recent workshops was with one of the largest beverage companies in the world and it focused on hydration,” Altieri says. She taught the group that water high in minerals is best for hydration—key knowledge if you plan on marketing to athletes, for example. “Minerals help us replace nutrients we lose while exercising or working or drinking; nutrients like calcium, sodium, potassium, and magnesium help us recover faster,” she says. Then, she taught them how to pair water with food and wine and also how to taste which waters were the highest in minerals. “The tastings start with the most bold and high in minerals and then we work our way down to the cleanest, super low mineral waters,” she explains.

So, what has this water somm learned about hydration? Different types of waters can help with different issues. “For example, if you want a water that will help with digestion, high bicarbonate [like Gerolsteiner] is your best bet,” she says. Hydration expert and sports medicine professor Sandra Fowkes Godek backs this claim, saying “one study has shown that it increases gastric emptying and small-intestinal movement, and it can also be helpful to reduce bleeding ulcers in the stomach.” (The study, however, was on rats.)

For a beauty boost, Altieri recommends reaching for a high silica water like Fiji because the mineral has been linked to helping with skin elasticity, by helping boost collagen production. According to Rachel Nazarian, MD, dermatologist at Schweiger Dermatology Group in New York City, “Silica is a vital element needed for the development of collagen, and helps improve strength and elasticity, which leads to youthful looking skin.” Still, she says the science is unclear about reaping the benefits of it through your water bottle. “Ultimately, the jury’s still out,” she says. “There is some evidence to suggest that silica from water may be a better source than that from diet—mostly cereal and veggies—but hopefully we will have more information about that in the next few years as this trend gains popularity.”

Wondering if fancy, expensive water is worth the splurge? Altieri says it depends on when you’ll be drinking it. “Expensive water, like expensive wine or coffee, is worth the indulgence and sip of luxury,” she says, adding that ones sourced from the North Pole, South Pole, or Spain are the best. “But after SoulCycle, I drink Smartwater or Gerolsteiner,” she adds. “You wouldn’t drink a bottle of Smartwater with a five course Michelin dinner, just as you wouldn’t drink a $100 bottle of Svalbardi after a cardio workout.” (Gasp—I would never!)

As for regular old tap water, Altieri says she’s not a fan and that she rarely drinks it—filtered or unfiltered. “Water, like wine, is a journey down ‘Tasting Avenue,'” she says. “I’d recommend exploring bottled mineral water for a better taste experience, and for a better cup of tea or coffee.”

But of course, not every trip requires you to walk down Tasting Avenue. So to avoid ending up at Destination Dehydration, it’s A-OK to take a swig of your S’well (no shame!) and save the scenic route for a time you can truly savor it.

Speaking of hydration, this is how much water you should drink every day. Plus, 11 add-ins to consider if you don’t like plain H20.