Here’s why: Sun tea gets warm but not hot. When you brew tea with hot water, any microorganisms in the water or on the leaves are pretty much killed. But with sun tea, you give them a nice warm bath in which they could reproduce. Usually, no big colonies form, and if they do it’s typically of benign organisms like Alcaligenes viscolactis and nobody gets hurt. Well, except for the li’l buggers once you drink ’em. (Update: While it’s not about sun tea specifically, Griffin Kelton tells a tea horror story that’s basically the same issue.)
Another reason not to make sun tea is because lots of the flavor that comes out of a tea leaf requires higher temperatures to make it into solution. Making sun tea, then, is to leave behind many of the flavors of the tea you’ve chosen.
Some like the flavor of sun tea for exactly that reason–it’s more mild than tea made the usual way. If that’s the case, make your tea using a cold-brewing process. Put the leaves in water and put it in the fridge overnight. Too cold for most microbes to flourish, but the added time allows for a similar milder tea flavor even at the lower temperature. Update: The image I’ve added shows the same tea, Dong Fang Mei Ren (aka Bai Hao Wulong, or Oriental Beauty). The cup on the left was brewed overnight in the fridge, while the cup on the right was brewed hot to ISO standards.
Now, I’ve heard that the US Centers for Disease Control have made some statement to this effect–that it’s best not to make sun tea because of the bacteria issue. However, I’ve never been able to find anything directly from the CDC about it. It’s been reported in several small-town newspapers, which gives some credence to the idea that the CDC frowns on iced tea, but I want to hear it from the horse’s mouth, so to speak.
So, if you can get me the official CDC statement/position on sun tea, I’ll give you a $15 credit in the Tea Geek store.
Rules: I have to be able to verify that what I get is really from the CDC. If I get several “correct” ones, the winner is the one I received first. Pretty much any format I can see is acceptable: link to official press release on the CDC website, scanned image of an official statement, video of a CDC official making an announcement at a press conference, whatever.
I haven’t been able to find any official documentation regarding “sun tea,” but the CDC claims on many occasions that iced tea (along side unpasteurized fruit drinks and coffee) may have Cryptosporidiosis colonization.
Link: http://su.pr/2aXXV0
Also, thanks for the reference.
This article from a Kansas school might explain why the CDC doesn’t have much info available on what’s wrong with Sun Tea. They don’t recognize tea as being much of a danger for transmitting any disease. The Article, on Iced Tea but Explaining
Well, do you trust the Virginia Department of Health to accurately report on the CDC? There’s a pdf of a 1996 newsletter here: http://www.vdh.virginia.gov/Epidemiology/Surveillance/Bulletin/pdf/VEB_1996/VEB%20Feb%201996.pdf
The CDC attention seems to have been initially drawn to commercial establishments. There is no mention of any actual documented disease as a result of sun tea in this report.
The point in question is presented in purely theoretical terms: “In addition, commercial food establishments and consumers wishing to reduce their exposure to a theoretical hazard may avoid brewing tea in tepid water or the practice of making “sun tea” by steeping tea bags in a container of water in the sun, because in these instances the tea is brewed at low temperature.”
“The practice of making “sun tea” by steeping tea bags in a container of water in the sun may be of higher theoretical risk than brewing tea at higher temperatures because it provides an environment where bacteria are more likely to survive and multiply.”
Rona doesn’t make sun tea here in Seattle, because it takes too long to do and isn’t worth it once it’s done. However, she did used to make it sometimes in Chicago, where it gets a lot hotter. I wonder if sun tea is safer (and more flavorful) in, say, Texas or Arizona than in our lovely Pacific Northwest.