Do I really need to descale my coffee pot and tea kettle?

If like so many people your day begins with a jolt of caffeine, you undoubtably have a tea kettle or coffee maker in your kitchen. And if you’ve ever looked closely at them while making up your morning brew, you may have noticed a crust or film inside. As it turns out, that annoying-to-clean buildup is composed of minerals from your water, and it’s what happens when you aren’t following your user manual (now, where did you put that thing?) and regularly descaling your kettle or coffee pot. But is it bad for your health? And can it affect how your beloved cup of joe (or bedtime chamomile tea) tastes? Here’s what experts say.

What is creating that buildup?

There are a couple of different films you may find on your coffee machine or tea kettle, Jason Tetro, microbiologist and author of The Germ Code, tells Yahoo Life. You may find a white scale, for example. This is calcium carbonate. It is common in areas with “hard water,” which means water high in mineral content such as calcium and magnesium carbonates, bicarbonates and sulfates.

Why do we see these deposits? Keith Warriner, professor of food science at the University of Guelph in Ontario, Canada, tells Yahoo Life that this scale occurs when calcium reacts with bicarbonate to form calcium carbonate, or limestone. Because this mineral is insoluble in water, it is therefore deposited as scale.

But there are different kinds of film you might find in your coffee makers or tea kettles as well. Tetro adds that it’s possible to also find a “biofilm” in these devices, which are made up of a “variety of microbes including bacteria and possibly fungi and viruses.”

“There have been studies that look at where these biofilms may exist and biofilms have been found in the drip tray, outlet, buttons, handle of the water tank and inside of the water tank,” Tetro explains. “In essence, the entire coffee maker can be a source for bacteria.”

Is the film or scale in my coffee maker or tea kettle dangerous?

In terms of a health risk, there isn’t much harm to the scale found in your coffee maker — at least, not on its own. However, if left unchecked over time, scale can damage the device itself, says Warriner, by blocking the tubes in a device and preventing the water from heating up.

The biggest risk of this, he notes, is that this blockage “can form points for molds to accumulate and these can grow on coffee residues,” adding that it also applies to the water filters in the coffee-pod units. This mold can lead to a bad taste to the water, but, in more serious instances, also cause ingestion of mycotoxins, says Warriner.

Mycotoxins are toxic compounds produced by certain molds that can contaminate food. Consumption of food contaminated with mycotoxins can result in symptoms like nausea and vomiting, while long-term health risks may include suppression of the immune system, cancer development and reproductive issues.

Biofilm is also a health concern. Tetro points to some pathogens in biofilm that can cause health risks, such as E. coli, Pseudomonas aeruginosa and Acinetobacter baumannii. However, pathogens that come into contact with water that is 160 degrees Fahrenheit (or 71 degrees Celsius) do not survive.

Tetro says that the biggest concern people should have with these devices may not be the scale or film at all. One place you may want to consider cleaning more regularly? The kettle handle, as it’s touched regularly and yet rarely cleaned. This is especially significant if you’re sharing the kettle with others, such as co-workers who use the same office kitchen space. “The whole machine should be thought of as a risk, not just where there is buildup,” Tetro adds.

How do you descale your coffee maker?

If you want to get rid of the scale or film in your coffee maker or tea kettle, Warriner suggests using white vinegar, which acts to convert the carbonate into carbon dioxide. While you can use 1% to 4% strength vinegar to treat scale, he says 4% strength is better at tackling mold. “Fill the vinegar into the water compartment and allow to sit for 2 hours, then start circulating for 30 minutes,” he explains. “Rinse with water, as you don’t want vinegar coffee.”

Tetro also recommends vinegar, suggesting you make a 50-50 combination of vinegar and water to clean your devices. “You can also use sodium bicarbonate and other commercially available descaling agents,” he says.

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