We know sun tea is very popular, but from a food safety standpoint, we advise against it. Sun tea is made by steeping tea bags in a large container of water placed in the sun for several hours to warm it. The problem is that the water only gets warm enough to encourage the growth of bacteria. Iced tea should be brewed at a minimum of 195 degrees F for 3-5 minutes, then stored in the refrigerator for up to one week. Following these guidelines will prevent bacteria growth in your tea.
There is some controversy over whether or not you should really worry about this. As a health professional, I feel obligated to be cautious and not recommend anything remotely unsafe. I suspect that the underlying rationale for this advice against sun tea is based upon the FDA’s recommended food safety guidelines for retail establishments, which states that there is a “danger zone” for food of 41 degrees F to 135 degrees F, the temperature range that allows bacteria growth. The longer a food spends in this danger zone, and the more often the food passes through this danger zone, the greater the risk of potential bacterial contamination. Having said that, the FDA does not list tea as a potentially dangerous food, and brewing tea is not specifically mentioned in the FDA Food Code.