Boiling Water

Water Vapor

When brewing coffee we spend a lot of time talking about the coffee itself, the roast by which it was transformed, and the brewing method that will affect it. The latter includes a key element that I believe should be addressed more often: Water.

More attention has been put into water quality recently but it is important that we re-emphasize that it is the main ingredient in any of our extractions. Hardeness, alkalinity, pH, and salinity are all important factors to consider when filtering water for extracting coffee, as well as the absence of chlorine. It is common for espresso machines or hot water towers to be connected to a water filter that somewhat controls these variables.

To properly extract ground coffee at sea level we must have water temperatures close to boiling point, and depending on altitude maybe even temperatures beyond boiling point. Whenever I prepare coffee, I boil filtered water and then let it slightly cool until the appropriate brewing temperature is reached. Recently I was told by someone that boiling water before infusing or extracting was a grave mistake. He explained that water is more than simple H20. Water has, apart from the above mentioned characteristics, several dissolved gases. One of the dissolved gases present in water is Oxygen. To clear any confusion I am not talking about the Oxygen in the water molecule (the O in H2O), but rather separate Oxygen gas (O2) that is dissolved in the liquid water. We see the evaporation of these dissolved gases as we boil water, they are the bubbles that rise from the bottom. Water doesn’t turn into its gaseous form, vapor, until boiling point is reached. And this, apparently, is important because the dissolved Oxygen gas is essential in transporting aroma molecules.

If this is true, we can conclude that the more we boil water the less potential it has to carry aroma and therefore flavor. This is worrisome to me given a lot of water boilers function by doing just that: boiling water (and then maintaining it at a specified temperature.) Also worrisome because to reach extraction temperatures at high altitudes without boiling water, a vacuum would be necessary. This would surely become a pain for any shop at altitude.

So I did an experiment, which was actually not easy to carry out. The idea was to cup the same coffee, with the only difference being boiled water vs non-boiled water. Except I couldn’t cup one and let it rest while I brewed the other because the speed at which coffee cools also affects its flavor, adding another not wanted variable to the experiment.

The solution was to use two kettles and pour the water at the same time on to both cupping bowls.

In the first kettle I added water and let it boil until the other kettle with water reached 207 F. I let it get to 207f  knowing it would lose a couple degrees on the pour. I am at sea level so boiling point is 212 F.

I then, at the same time, poured non boiled and excessively boiled water into cupping bowls with the same coffee. At 4 minutes I broke, cleaned, and then waited until they cooled to 160 F to taste.

The Results:
I am surprised. There was a massive difference in taste. I can’t however say one was better than the other. The bowl using the non boiled water had more high notes and more noticeable acidity. The one using the boiled water wasn’t as bright as the other but had a pronounced sweetness and seemed cleaner.

This is obviously not definitive, and I will continue testing this theory. I also would be interested in seeing how this would work with tea.


2 Responses to “Boiling Water”
  1. The importance of water is almost always underplayed. Water is just water, like produce is produce, right. And yet even in the specialty coffee world (in my eyes, a bunch of smart people making incredibly exact and precise coffee extractions for a crowd of mostly caffeine fiends), water quality is not considered very often.

    There is a simply way to get Chlorine out of water. All you do is let it sit for 30 minutes with a cloth on the top. But of course, FDA regulations do not let coffee shops do this. And who wants to invest in expensive reverse osmosis technology?

    On another note, I was at a tea tasting in Boulder, CO the other day, and tasted tap water and water treated with some kind of mineral. The treated one tasted very different, and the teas resulting from it did as well. Like you said, it is a matter of opinion what is better and what is worse in taste. But when it comes to nourishment, I certainly prefer clean water in my tea and coffee flavored water.

    • lalinpv says:

      Tap water, although mostly just as clean as bottled or filtered water, is added with chlorine to prevent any bacterial/viral growth as it is transported from filtration to tap. Chlorine evaporates if you let water sit like you mentioned before, but it would be a safety hazard in a commercial setting to do so, and also probably inconvenient. Although reverse osmosis technology is quite expensive there are other water filters that are very effective at filtering out chlorine and are very pocket friendly. The ideal water for brewing coffee has very specific standards that are hard to achieve unless customized (, but spring mineral water is the best natural resource. As far as nourishment goes, some filtered water can be too filtered. For example, tap water in the USA is added with fluorine which greatly increases dental health, especially in children. Although water filters, including home filters (Brita, Pur, Etc.) do filter out chlorine and some taste affecting metals from piping (copper, lead) they also filter out fluorine. And in the event that a pitcher and not faucet filter is being used it is more likely bacterial contamination will affect the now un-chlorinated sitting water.

      Do you happen to know what Mineral was used to treat the water used for tea?

      There is a Japanese company that specializes in magnetism and has a special water filter that filters water through activated carbon (Brita style) but then has rocks that provide the water with silver, magnetite, and calcium that alkalinize the water. ( Check them out! Under Product technologies check out the PiMag water. They even have a shower filter because they believe that hot water evaporates chlorine while you shower making it easy to inhale and therefore bad for your lungs. Let me know what you think!

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