Nancy Haberstich, creator and founder of Nanobugs Inc. writes in the Lincoln Journal Star that the appeal of sun tea is the ease at which you can make it — pop a bunch of tea bags in a big jar of water and set it in the sun.
Microbes can easily contaminate tea leaves. When added to water, these microbes can be revived and start multiplying — especially if they sit in warmer temperatures of 40 to 140 degrees.
Tea made with the sun’s rays will not get hotter than 130 degrees, Haberstich said. The caffeine in black tea will help prevent some bugs from flourishing for a few hours, but its effects won’t last beyond that. Herbal teas are an even worse bet for brewing in sunlight because they lack caffeine.
For safer iced tea, boil water and pour it over tea bags or tea leaves. Steep to desired concentration, then add ice and serve. Iced tea makers are also safe alternative, if they heat water to 195 degrees.
A new trend is the “cold brew” method — which is safe as the tea or coffee is “brewed” overnight in a refrigerator (which is colder than 40 degrees).