Green Tea Steeped in Bottled Water Has More Antioxidants, Cornell Study Finds
Summary: Researchers report a boost in beneficial antioxidants when green tea is brewed with bottled water rather than tap water.
Source: Cornell University.
Key finding: Green tea brewed with bottled water contains higher levels of the antioxidant epigallocatechin gallate (EGCG) than green tea brewed with tap water. The bottled-water brew was reported as more bitter, while the tap-water brew tended to taste sweeter.
Study background and results
Researchers at Cornell University’s Sensory Evaluation Center published the findings in the journal Nutrients on January 3. In sensory tests involving more than 100 consumers, participants generally preferred the taste of green tea brewed with tap water over the same tea brewed with bottled water. The panel described the tap-water infusion as having a sweeter flavor profile. By contrast, green tea prepared with bottled water measured roughly double the amount of EGCG compared to tea brewed with tap water, which corresponded with a more pronounced bitter note.
Robin Dando, associate professor of food science at Cornell, summarized the trade-off: “If you’re drinking green tea for its health properties, you should be using bottled water. If you’re drinking tea for taste, tap water is better.”
Black tea comparison
The study also tested black tea and found that consumers could not reliably distinguish a taste difference between black tea brewed with tap water and black tea brewed with bottled water. According to lead author Melanie Franks, this suggests that the extraction and flavor dynamics for black tea are less sensitive to common variations in water composition than those for green tea.
Why water composition matters
The research team proposes that ordinary dissolved minerals commonly found in tap water — such as calcium, iron, magnesium, sodium and copper — may reduce the efficiency of extracting EGCG from tea leaves. Bottled water, which often has lower concentrations of these minerals after filtration or processing, appears to extract EGCG more effectively. As Dando explained, “With purer water, you get more health benefits out of the tea.”
The practical implication is straightforward: people who drink green tea primarily for its antioxidant benefits may maximize those benefits by using bottled or otherwise low-mineral water. Conversely, drinkers who prioritize flavor and a sweeter tasting cup may prefer brewing with their usual tap water.
Expert comments and study team
Melanie Franks, MPS ’18 and the study’s lead author, is a tea specialist who has experience teaching culinary professionals. She noted that while subtle flavor differences were detectable for green tea, average consumers could not tell a difference when tasting black tea prepared with different types of water.
Robin Dando and the Cornell team emphasize that these results reflect measured differences in EGCG concentration and consumer taste perceptions under the specific conditions of their tests. They do not suggest that tap water is unsafe to use for tea, only that its mineral content can alter antioxidant extraction and perceived flavor.
Funding: The research was funded by Cornell University.
Source: Cornell University press materials and the study published in Nutrients.
Publisher note: Organized reporting was provided by the original outlet covering the research.
Image credit: The image used in the original report is in the public domain.
Original research: The study, titled “The Influence of Water Composition on Flavor and Nutrient Extraction in Green and Black Tea,” is available through the Cornell University publication channels and the journal Nutrients.
If your goal is maximizing the antioxidant content of green tea, consider using bottled or filtered water with lower mineral content when you brew. If you prefer a sweeter, less bitter cup, tap water may produce a more pleasant flavor. For black tea drinkers, this study suggests the choice of water is less likely to affect perceived taste.
These findings highlight a simple and actionable way to adjust your tea experience, depending on whether you prioritize health-related compounds like EGCG or a specific flavor profile.