Sun tea is not considered safe by food safety standards. The core problem is temperature: water sitting in a glass jar in the sun typically reaches only about 130°F, which falls squarely in the “danger zone” between 40°F and 140°F where bacteria multiply rapidly. That’s well below the 195°F the CDC recommends for brewing tea. While the statistical risk of getting sick from any single batch is low, the method consistently creates conditions that favor bacterial growth over safe brewing.
Why Sun Tea Sits in the Danger Zone
Bacteria thrive between 40°F and 140°F. Foods and beverages need to either stay below that range (refrigerated) or get above it (cooked or brewed with boiling water) to stay safe. Sun tea, by design, lands right in the middle. Even on the hottest summer days, a glass jar of water in direct sunlight generally won’t climb past 130°F. That’s warm enough to extract some flavor and color from tea leaves, but not hot enough to kill bacteria already present in the water or on the leaves themselves.
For comparison, the CDC recommends brewing tea at 195°F for three to five minutes. That temperature is high enough to neutralize common waterborne bacteria. Sun tea misses that mark by more than 60 degrees, and it sits at its lukewarm temperature for hours, giving any microorganisms present a long, comfortable window to reproduce.
The Bacteria That Grow in Sun Tea
Tea leaves are a natural product that can carry soil-dwelling microorganisms. One species worth knowing about is Alcaligenes viscolactis, a ropy bacterium commonly found in soil and water. If your sun tea develops a thick, syrupy, or stringy appearance, that’s a telltale sign this bacterium has taken hold. At that point, the tea should be discarded immediately, and the jar should be thoroughly sanitized before reuse.
Even when sun tea looks perfectly normal, bacteria can still be present in numbers that don’t visibly alter the liquid. You won’t always get a warning sign like unusual texture or off flavors. The risk compounds if the tea sits at room temperature for several hours after brewing, which is common at summer cookouts and picnics where sun tea is most popular.
Does Adding Sugar Make It Worse?
It depends on when and how much. In high concentrations, sugar actually inhibits microbial growth, which is why jams and syrups resist spoilage. But the amount of sugar most people stir into a pitcher of iced tea is nowhere near that concentration. A few tablespoons of sugar in a quart of lukewarm water provides a modest additional energy source for bacteria without being concentrated enough to suppress them. If you do sweeten your tea, adding sugar after brewing and chilling is a better practice than letting it dissolve during the hours-long sun brewing process.
Safer Ways to Make Cold Tea
If you love the mellow, smooth taste of sun tea, cold brewing in the refrigerator produces a very similar result with far less risk. Place tea bags in a jar of cold water and refrigerate for 6 to 12 hours. The water stays well below 40°F the entire time, keeping bacterial growth to a minimum while slowly extracting flavor. The taste profile is comparable to sun tea: less bitter, less tannic, and slightly sweeter than hot-brewed tea.
Hot brewing followed by cooling is the other safe alternative. Boil water, steep your tea bags at 195°F or above for three to five minutes, then let it cool before transferring to the refrigerator. This method kills bacteria during the brewing step and produces a stronger, more traditional tea flavor. You can dilute with cold water or ice to speed up the cooling process.
Whichever method you choose, brew only as much as you’ll drink within a reasonable window. Refrigerated brewed tea stays fresh for about 24 to 48 hours. Tea left at room temperature should ideally be consumed within a few hours.
If You’re Going to Make Sun Tea Anyway
Some people have been making sun tea for decades without incident and aren’t planning to stop. If that’s you, a few precautions can reduce (though not eliminate) the risk.
- Start with a clean jar. Wash your jar with hot, soapy water before every use. For extra protection, you can sterilize it by submerging it in boiling water for 10 minutes.
- Use fresh, clean water. Tap water from a treated municipal supply is safer than well water for this purpose.
- Limit brewing time. Don’t leave the jar in the sun longer than three to four hours.
- Refrigerate immediately. As soon as you bring the jar inside, move it to the refrigerator. Don’t let it sit on the counter.
- Skip the sugar during brewing. Sweeten individual glasses after pouring rather than adding sugar to the whole batch while it sits in the sun.
- Check the appearance. If the tea looks thick, syrupy, or has any stringy texture, throw it out. That’s a sign of ropy bacteria.
- Drink it the same day. Don’t store sun tea overnight, even in the fridge. Make a fresh batch each time.
The honest reality is that most people who drink sun tea won’t get sick from it. The risk on any given batch is small. But the method reliably creates conditions that food safety guidelines exist to prevent, and equally tasty alternatives don’t carry the same concerns. Cold brewing in the refrigerator takes the same minimal effort with a fraction of the risk.