So this guy walks into a tea shop… A joke? No, a story with a lesson in it.

This fellow clearly knew what he wanted when he walked into my shop. A traditional Earl Grey. I pulled out a couple of options and let him give them a sniff. He chose one, and then specified exactly how he wanted it brewed.

“Three minutes.” Easy. Check.

“Two tablespoons of milk.” No problem.

“212 degree water.” Well, now we have an issue.

What he really wanted was boiling water. This fellow lived quite close to sea level, and to him, boiling meant 212°F (100°C). What he didn’t know was that the boiling point of water changes with your altitude. At sea level, it is indeed 212°F, but the boiling point drops by about a degree for every 500 foot gain in altitude. Take a look at the graph above. The blue dot represents where my tea shop was, at an altitude of very close to 5,500 feet (1,680 meters). That makes the boiling point of water in the shop 202°F (94.4°C).

I explained to him that water simply can’t reach 212 at this altitude. It turns to steam at 202. I told him I would be happy to make his tea using boiling water, however, which is what everyone recommends for black teas like Earl Grey.

He wasn’t buying it. To him, tea must be made with 212° water. Period. End of sentence. I tried to explain that would mean he couldn’t have tea unless he was sitting on the beach. He said I was making excuses because I couldn’t boil water properly.

Luckily for me, my electric kettle lies

In the tea shop, I used Zojirushi electric kettles that keep water at a precisely specified temperature. I had one for black tea and one for green tea (I mixed it with cold water to get lower temperatures), so the right temperature water was always available at a moment’s notice.

I noticed something interesting soon after I bought my first Zoji: If you press the “quick temp” button, it will heat the water until it reaches your specified temperature. If you don’t, it will bring it all the way to a boil and then let it cool to your specified temperature. The interesting part is what happens when the water comes to a boil. It displays a temperature of 212°F (see the photo above). This, of course, made me mistrust their temperature readings, but more on that in a moment.

I added some water, told the fellow in the tea shop to wait a moment, and let the water come to a boil. I showed him the (completely wrong) temperature readout on the Zoji, made his tea, and let him leave my shop thinking he won. *sigh* The customer isn’t always right, but sometimes it’s not worth the trouble of introducing facts, no matter how solid the facts are and how easy they are to verify.

Postscript

As I said, the inaccurate temperature shown at boiling point is indisputably, inarguably, wrong. And I can’t see any way it was an accident. Zojirushi must have done it on purpose, as their temperature sensor in the water can’t possibly register 212°F at an altitude this high. Perhaps they did it to cut down on tech support calls, rather than trying to explain the bad reading.

I used a thermometer that I trusted to check the “hold” temperatures of 208, 195, 175, and 160. All of them were accurate to within a degree or two. That means that for everyday usage, it’s okay. It just means the marketing folks at Zoji must have overridden the engineers, who certainly know better.

As I write this, I’m drinking an excellent Tanzanian green tea. The fluffy twisted leaves provide a great “agony of the leaf” display as it steeps and the tea tastes excellent. I steeped it at 175°C for two minutes, and got three infusions from the leaves.