A cup of tea left overnight is poison.

Yesterday was National Iced Tea Day.  

When I was growing up, my mom brewed her iced tea on the front porch in the sun.  The Centers for Disease Control and Prevention (CDC) calls the tea she made “sun tea.”  

Foodborne pathogens can survive in brewed tea, but for tea brewed at an appropriate temperature–with water hot enough to kill pathogens–the issue of safety is primarily one of storage conditions and ensuring the tea dispenser has been cleaned and disinfected before use.  

The CDC summarized its findings on iced tea safety with the following points:

1. Tea is a beverage with little history of disease transmission. At present, no outbreaks of infection have been reported to CDC that were clearly associated with the consumption of tea.

2. Tea leaves may be contaminated with coliform bacteria. If iced tea is brewed at inadequate temperatures or in an improperly cleaned urn, or if it is stored for too long, it may grow coliform bacteria, most frequently Klebsiella and Enterobacter, and less commonly E. coli. In particular, the faucet of iced tea urns may provide a nidus for bacterial contamination.

3. Food handling errors that lead to the introduction or that encourage the replication of microbial pathogens in brewed tea could theoretically result in human disease.

4. Brewing iced tea at an appropriate temperature in a thoroughly cleaned urn and limiting the time held at room temperature before serving will minimize the theoretical risk of bacterial contamination.

Recommendations for Iced Tea Safety

* Iced tea sould be brewed at 195 F for 3-5 minutes.

* Iced tea should be stored for no longer than 8 hours.

* The tea brewer, storage dispenser, and faucet should be cleaned daily.

The CDC stated that redesigning tea dispensers to be more easily dismantled and cleaned could further reduce the theoretical risk of bacterial contamination of iced tea.

Sun Tea

According to the CDC, “The practice of making ‘sun tea’ by steeping tea bags in a container of water in the sun may be higher theoretical risk than brewing tea at higher temperatures because it provides an environment where bacteria are more likely to survive and multiply.

I’ll have to tell my mom.

Suppose you made a cup of tea (the real tea, not bagged, and not a fruit drink) with no additions, but you forgot about it while doing other things (house stuff, homework, your job) and it has now been 2 hours since you made it. The tea is cold, possibly bitter, and a significant portion of its flavor is gone (this has been the usual result for me with all real teas). It's not so good any more, but is it safe to drink now?

As the saying goes, a cup of tea left overnight is poison. How true is that in terms of actual hazards?

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01/7The logic of reheating tea

In short, yes. It has happened with all of us at some point. We brew a hot cup of tea but it just so happens that we leave it unattended for long and sometimes even forget about it. Reheating tea has its advantages. It saves money, energy and also reduces our carbon footprint. However, many of us have been told about the dangers of having reheated tea. But throwing it seems like such a waste! So what should you do? Here is what happens to tea when reheated and why should you avoid having reheated tea.

02/7​What happens to tea when it is reheated?

You always have the choice to reheat the tea. However, doing so might steal many of its flavours, nutritional properties and aroma. If you have left your tea abandoned for more than four hours, it is downright not recommended to reheat the tea as it may harbour mould and bacterial growth. If you are looking to reheat Indian chai made with milk and sugar, know that it only develops bacteria and other contaminants at extra speed. Warming your herbal, fruity or milk tea will take away several of its beneficial properties. Some volatile compounds such as essential oils and labile are also present in the tea, and they escape when subjected to too much heat.

03/7​Brewing vs boiling

Many people are not aware of the fact that teas are not meant to be boiled and never with milk and sugar. The water is first boiled and taken off the flame. Then the tea leaves are left to steep in them for 3-4 minutes. This process is known as ‘brewing’. If you make the tea by boiling the tea leaves in water, it may already lose many of its nutritions, flavours and fragrances. Imagine what doing it again would do to your cuppa!

04/7​Why should you avoid reheating tea?

First things first, do not reheat the tea if it has been left at room temperature for anywhere between 4 to 8 hours. If you forgot to have your tea for a maximum of 10 to 15 minutes, it is safe to drink. The food poisoning bacteria grow in brewed teas that are exposed to heat between 41 to 140 degrees Fahrenheit. The case is even worse with milk teas, which can also gain an unpleasant taste and grainy texture when reheated. The presence of milk results in faster accumulation of bacteria, and only reheating the tea will not kill them. Problems might get dangerous if your tea develops moulds. They might not be visible to the eye and can be easily missed. Drinking such tea even when reheated can cause stomach upset, diarrhoea, cramps, nausea, inflammation and many other digestive issues.

05/7​Impacts the taste

Apart from making the tea lose its nutritional properties and become contaminated, reheating the tea can also negatively impact its taste. Tannins are polyphenols responsible for the colour and flavour of the tea. When we leave the brewed tea in the saucepan for an extended period of time or reheat it later, it causes the leaves to release excess tannins and makes the tea taste bitter. It might not be palatable to people who do not prefer strong tasting teas.

06/7​How to reheat tea? (If you must)

Even though reheating cold tea is not recommended, it is possible to warm it for those who must. Place your cold tea in a clean mug. Boil water in another utensil and place the mug in the boiling water for 3-4 minutes. It is called the ‘double boiler’ method. Do not expect the tea to taste fresh or become piping hot. Consume it when it is lukewarm. For the sake of your digestive health, do not reheat teas exposed to room temperature for more than four hours.

07/7​Alternate uses for your cold herbal teas

If you have a mug of cold herbal tea that you don’t know what to do with, we can suggest a bunch of interesting alternative ways to use it. Tea contains a burst of nutrients, and you can water your plants with it to provide them with some extra nourishment. You can also wash your face with it as it is considered as a great disinfectant and grease remover. You may also use it to clean the burnt and crispy bits of rice at the bottom of the pan!

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