Beyond thirst: the water sommelier on the science of hydration 

You’ve heard of a wine sommelier, but have you ever heard of a water sommelier? That’s the title held by Paul Jacob, a Senior Water Technology Manager at Danone Research & Innovation (R&I). Where a wine sommelier might remark on a wine’s oaky flavor or notes of vanilla, Paul’s trained palate is able to identify a water’s mineral content, distinguish the taste of magnesium from calcium, or even identify the specific type of bubble in a sparkling water. As a water sommelier, he sits at the intersection of hydrogeology, chemistry, sensory science, and human physiology, looking at how people can make the daily chore of hydration much more pleasurable.

Paul Jacob, a Danone water sommelier, is dedicated to celebrating water and helping people understand the science behind the taste of different waters. 

“A lot of people have a deep-rooted assumption that water is tasteless and interchangeable,” says Paul. “But that’s just not true.” And in fact, beneath the surface, most people do have preferences between waters – whether that’s an inclination towards the tap water from the specific town where they grew up, or an opinion on sparkling versus still water.

“Many consumers don't have the words to describe the feeling of what they like or don’t like about water. So, we give words to the sensations,” Paul explains. 

Helping people to understand the taste of water, translating chemistry to lived experience, and celebrating water in all its forms, is at the heart of his role as a water sommelier.

Water’s taste comes down to its minerality: As water travels through geological layers, it dissolves minerals such as calcium, magnesium, sodium, bicarbonates, sulphates, chlorides, and silica. The concentrations of these ions, and how they interact with our taste receptors, determines the taste and texture of the water.

Waters whose mineral composition closely mirror that of our own saliva tend to feel smooth and almost invisible on the palate. But when the mineral balance of water differs from what our mouths are used to, we notice it. 

The mineral balance can really affect the way water feels in the mouth: whether it seems light or substantial, sharp or round, instantly refreshing or subtly complex. Take magnesium bicarbonate, for example. At low concentrations, it can taste faintly sweet, but as levels rise, it shifts towards a bitter flavor. Meanwhile sodium bicarbonate (essentially baking soda) can create a faintly soapy, frothy sensation. Each ion leaves a different signature on the tongue.

There may be objective differences between waters – but taste is, ultimately, personal. Our taste preferences are also shaped by the water we drank while growing up (what sommeliers call a person’s ‘reference water’), and by our individual differences in saliva composition and prior exposure. 

In France, there is more of a preference for low mineral waters, while in Germany there is more demand for higher mineral waters. In some countries, sparkling waters are popular, with carbonation that adds an acidic taste and bubbles that add a whole new mouthfeel dimension. 

“It's a bit like wine,” Paul explains. “Someone raised on bold red wines might find a delicate Burgundy thin; someone raised in the Alps might find a low-mineralized water unremarkable. Neither is wrong, the palate simply expects what it knows.”

Sommeliers can come from diverse professional backgrounds, but Paul’s own background is as a food engineer and environmental engineer, with a PhD on membranes and desalination. Once at Danone R&I, he worked alongside colleagues who shared his enthusiasm for water – and decided to pursue official certification, signing up for an intense two-week course at the Doemens school in Germany. 

“You taste a lot of water,” Paul recalls. “Germany has a very mature market of water, with over 500 mineral waters in the market, and it’s very local and very, very specialized. After two weeks of coursework, we had to pass an exam to call ourselves water sommeliers.” But education is never finished: “If you don't stay in the business of water, you will lose the sense of tasting. And there is always more to learn.”

There are about 200 active water sommeliers in the world, and with four water sommeliers within Danone R&I, Paul is part of a ‘crack team’ of sommeliers. In his day-to-day role as Senior Water Technology Manager, he looks at the mineral composition of water – and as a trained sommelier, he adds the dimension of taste.  

“The job is really about translation: turning complex scientific notions into something meaningful that connects what's in the water and its origins, to what happens in the tongue,” Paul says. “All waters are beautiful, and we help people understand and appreciate its particularities.”

Ever wondered why a beer brewed in Belgium will taste different from one brewed in America, or Germany, or Ireland? One of the main reasons is the local water supply. The regional mineral fingerprint of water affects the flavor of whatever it’s mixed with or consumed alongside – whether that’s tea, cheese, coffee, chocolate, or yoghurt.

“Water is often the primary ingredient in a recipe and almost always the most overlooked. Its mineral composition can transform a dish or a drink at every stage of preparation,” explains Paul. 

In coffee or tea, dissolved minerals directly affect how aromatic compounds are extracted from the grounds or leaves.  

“Take a high-quality green tea, and brew it twice: once with your usual tap water, once with a low-mineralized natural mineral water,” Paul suggests. "Use exactly the same quantity of leaves, exactly the same steep time, exactly the same temperature. Then compare.” The differences in astringency, aroma, and color can be striking.

In cooking, calcium and bicarbonates can fix chlorophyll, or neutralize acidity, and interact with proteins in ways that change texture. Another consideration is sodium content: when eating a salty cheese, you may actually want a water high in sodium, to neutralize the salt on your palate and allow other, more subtle flavors to emerge.

“The right water doesn't just avoid harming a recipe, it actively enhances and harmonizes the final sensory experience of the dish or product,” Paul says. 

In recent years, the culinary world has increasingly woken up to this fact. Paul and his colleagues have run many tastings with top chefs, including Michelin star chefs – demonstrating the power of water as an ingredient in its own right. 

At his tastings, Paul loves to watch people’s love for water grow as they understand more about where their water comes from. “Natural mineral water and spring waters are the result of a slow, ancient process that engineers cannot easily replicate,” he tells us. “Rainwater infiltrates protected land, journeys through geological layers for years or decades or some cases millennia and is naturally filtered and enriched with minerals along the way as it meets the specific rocks or geology. 

“As water journeys through the aquifer, it reaches a state of chemical equilibrium. That journey gives each natural mineral water a stable, unique composition. Stable is the key word: it defines how the water tastes; ensures it is consistent year after year. Natural mineral water is essentially the signature of a specific territory and ecosystem.”

Water is critical to nearly every function in the body, from transporting nutrients and oxygen to cells, to digestion, to helping our kidneys remove toxins and waste. Adults are advised to drink six to eight cups of water – roughly 1.5 to 2 liters – per day, though the amount needed can vary from person to person. 

The consequences of under-hydration go further than most people realize. Research conducted by Danone R&I in collaboration with Liverpool John Moores University, and published in the Journal of Applied Physiology, found that people who drank less than 1.5 liters of water per day showed significantly higher levels of cortisol (the body's primary stress hormone) compared to those who were well hydrated. 

Regardless, many people find it difficult to drink enough water. That’s where a critical factor comes in: enjoyment.

“In my opinion, hydration is not purely a physiological problem; it is behavioral,” says Paul. “A water that feels pleasant, smooth, and genuinely refreshing lowers the barrier to drinking it. Taste is infrastructure for hydration – so people will always drink more of the water they enjoy.” 

1. https://www.nhs.uk/live-well/eat-well/food-guidelines-and-food-labels/the-eatwell-guide
2. https://journals.physiology.org/doi/full/10.1152/japplphysiol.00408.2025

Paul Jacob is a Senior Water Technologist and Water Sommelier at Danone, with a background in water engineering and advanced membrane filtration technologies. With experience spanning innovation scouting, process development, and knowledge valorization through patents and scientific publications, he works at the intersection of water quality, safety, and taste. Paul brings a rare dual perspective—combining rigorous science with sensory understanding—to his work on water technologies, from industrial filtration and desalination to emerging, beyond‑bottle models. Curious by nature, he is driven as much by discovery and experimentation as by practical impact.