The Dark Side of Sun Tea? Try Cold Brewing!

Cold Brew Tie Guan Yin (Photographer: Brodie Standen, Image Courtesy: Queensland Art Gallery | Gallery of Modern Art)
Cold Brew Tie Guan Yin (Photographer: Brodie Standen, Image Courtesy: Queensland Art Gallery | Gallery of Modern Art)

UPDATE: Some of the information in this article needed updating due to more recent studies and some exaggeration of the risk involved.

One of the most popular teas in summer is “sun tea” – tea that is brewed by leaving a clear container with tea in it out in the sun for a few hours. It has a certain appeal because it is such an easy process, not to mention the fact that tea looks awfully pretty in the sunlight. This method will not get hotter than 130°F (54.44°C) and is supposedly not hot enough to kill bacteria in the water or in the tea leaves. Water temperatures for a regular infusion ranges from 160°F to 212°F (or the boiling point). This may not kill all undesirable microbes either but will certainly kill a lot more than that lower temperature.

The other issue that some people report is that sun tea generally sits around for a lot longer than hot tea, so that the bacteria has a chance to multiply and become problematic. They say that in essence, the sun tea method is a lot more like making tea in a contaminated Petri dish than a teapot. One such statement is from Is Sun Tea Safe?, on the Colorado State University Extension SafeFood Rapid Response Network. Or you can read, a reliable source for verifying or dispelling rumors and urban legends, stating that sun tea is unsafe.

Of course, every summer people brew and drink gallons and gallons of sun tea and do not get sick, so the risk is really quite minimal. However, there are excellent alternatives for making iced tea:

  • Boil the water before you make sun tea to prevent the bacterial risk (but once you’ve gone to that effort you might as well just hot brew the tea in the normal fashion and then cool it in the refrigerator).
  • Cold-brew your tea, thereby avoiding using the stove on hot days. Steeping tea leaves in cold water for a few hours in the refrigerator produces excellent tasting cold tea and also works quite well for many tisanes (non-tea infusions). Use a Mason jar or similar, fill with loose leaf tea, and then strain after steeping (usually about six hours, depending on how strong you prefer your tea) into a second jar.

While there’s really no compelling reason to make sun tea when you want to drink iced tea, you’re an adult and can assess the risk for yourself. Take the sun tea containers that you’d put out on your porch and put them in your refrigerator instead for a cold-brewed tea that tastes as good or better.

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13 thoughts on “The Dark Side of Sun Tea? Try Cold Brewing!

  1. Pingback: Making Your Own Iced Tea « Tea Blog

  2. Pingback: Keeping Cool with Iced Tea « Tea Blog

  3. bek

    This doesn’t make sense. If there is bacteria in the tea or water, it won’t be killed by cold brewing so that’s not any safer. Even if the cold keeps the bacteria from growing, they would still be there. And shouldn’t you be more concerned about your water source or what tea you are buying if they are so bacteria laden? Also, unless sweetened prior to sun exposure, what food would the bacteria have to grow on? Has anyone ever heard of anyone actually getting sick from sun tea? Maybe I am just biased b/c I don’t trust info from CO State (wink, wink ;). Thank you for the info on cold brewing though. I am a cold sweet tea drinker myself so I will give this method a try.

    1. ivyhoff

      I agree. If there was any bacteria in the tea or water, I’d want to kill it, not simply inhibit its growth. Besides, if the bacteria is coming from your water, aren’t you going to get sick just drinking the water from the tap, nevermind making tea out of it.

  4. Having read your article on Sun Tea, I wonder why this has not come up before. My husband and I have been drinking sun tea for 34 years. We live in the Southwest where Sun Tea is very common.
    So, my question is can we boil the water for Sun Tea put in the bottle and let it sit out for two hours, take the bags out and refrigerate it?

    1. Tim

      I wish I lived in the Southwest where Sun Tea is common. O, Sun, if you come back, I swear I’ll treat you right this time!

      Re boiling the water: that’s a very good idea.

  5. Thanks for the enlightening article. We just had sun tea yesterday, thought it would be easy and fun. I do remember now about the refrigerator method and had forgotten. Thanks for jogging my memory.

  6. Melissa

    I recommend using an electric kettle. Mine heats the water in the fraction of time it takes to heat water on the stove top without heating up the whole house. Great article!

  7. If sun tea does not kill bacteria because the water doesn’t get hot enough, I’d imagine cold-brewed tea would not either. Why doesn’t cold-brewed tea have the same problem?

    1. The temperature inside a refrigerator is cold enough to inhibit the growth of bacteria, which is the primary reason we use them for storing foodstuffs. Basically it’s the mid-ranges of temperature – not extremes of hot or cold – that are ideal for most types of bacterial growth.

  8. Great article! I agree that sun tea looks pretty in a jar and it is rather cool to brew tea in the sun, but there is no loss in flavor if one brews tea in the fridge. I believe that you recommend Ceylon for iced tea? I rather like it myself.

      1. Sencha (plain or flavoured varieties) is also really nice cold-brewed, if you want a non-black iced tea – you might want to experiment to find the best length of steeping time, but generally it produces a beautifully clear, sweet tea, truly refreshing!

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