Brew green tea in bottled water instead of tap water to reap its health benefits, scientists have said.
The result is a tea with almost double the amount of the antioxidants, according to a study by Cornell University.
However, if you're drinking green tea for taste, tap water will yield the best cup, ensuring it's not too bitter.
EGCG (epigallocatechin gallate) is a natural antioxidants found in green tea, shown to be beneficial for the brain and heart in studies.
Celebrities including Jennifer Aniston are fans of the Asian brew, believed to be an aid for weight loss, energy and stress control.
To conduct the tests, 2.5g of green tea was weighed out into pre-warmed Gaiwan tea brewing vessel with 125ml of water at 80°C (176°F).
The green tea infusion was brewed for three minutes and then strained through a fine mesh strainer.
EGCG in the tea infusions was measured by the researchers, and around 100 tea drinkers were recruited to taste the tea.
After giving details on their normal tea drinking habits, the volunteer evaluated six cups of tea - three black, and three green.
They rated each tea sample on a scale of one to nine for how much they liked its taste and appearance.
They were also taught how to use a specific scale to measure the sweetness, bitterness, sourness and earthiness of the brews.
Results showed levels of
ECGC in the green teas were 'drastically reduced' in those brewed with boiled tap water. No effect was noticed in the black teas.
The researchers said this is because the levels of calcium, magnesium and iron are higher in tap water.
Professor Robin Dando, one of the authors of the study, said: 'Bottled water is able to extract the EGCG more efficiently.'
He added this is because calcium and magnesium have been filtered out of the 'purer' water, and iron concentration is also 'brought down a notch'.
Professor Dando added: 'With purer water, you get more health benefits out of the tea.'
Consumers liked green tea brewed using tap water more than using bottled water, because it produced a sweeter taste.
But there was hardly any difference in black tea brewed in either tap water or bottled water.
The findings were published in the journal Nutrients.
'The average consumer for black tea isn't able to tell the difference,' said lead author Melanie Franks.
'Whether it was tap water or bottled water, the taste differences are too subtle.
'Since black tea has fewer catechins than green tea due to the oxidation process in manufacturing, the type of water used seems less important to the everyday tea drinker.'
Jennifer Aniston 'drinks green tea throughout the day,' according to an interview with
Green tea, which originated in China and is made from Camellia sinensis leaves, is a well-researched area.
ECGC has been found to stave off or slow the progression of Alzheimer's disease in a 2015 University of Missouri study, when combined with physical activity.
But other components found in green tea - caffeine,
amino acid L-theanine and other catechins have shown possible health benefits in studies.
These include lower cholesterol, a lower risk of Parkinson's and even cancer. They have also been shown to boost metabolism.