If you’re one of the people who have fallen into the coffee rabbit hole, then this post is for you. Since you’re here, then you probably know that water plays an essential part in the coffee brewing process.
Naturally, at some point, all of us coffee lovers, have asked ourselves if using distilled water for our coffee will improve our brew’s flavor and overall quality.
After all, distilled is the purest water, so it may have a positive impact on the extraction efficiency, right?
Furthermore, at a first glance, it seems like a good idea to make your filter or espresso coffee with distilled water to enhance the final flavor. Because distilled water is so pure, it may seem that it won’t overshadow or negatively affect your specialty coffee beans’ aromas and tasting notes.
In this post, I’ll comment on this assumption and shed some light on the subject matter.
I will help you decide whether it’s worth trying to make espresso, cold brew, or filter coffee with this type of water.
What’s also worth noting is that some people are drawn by the idea of using distilled water in their coffee maker, as they think that doing so will prevent the formation of limescale.
It does sound tempting – by adding only distilled water, your machine won’t ever need descaling.
Nevertheless, using this type of water may not be as safe for your coffee maker as you’d wish.
So if you’re wondering whether it’s good or bad to use distilled water in your espresso, Keurig, Nespresso, or other coffee brewing device, you will undoubtedly find helpful insight in this guide.
So let’s dive in!
Distilled Water for Coffee: Is it a Good Idea?
Using distilled water for coffee making isn’t advisable.
The lack of dissolved minerals (such as magnesium and calcium) in this type of water, has a negative impact on the extraction process, which results in an unbalanced, overly acidic, and overall unpleasant coffee flavor.
Furthermore, pouring pure distilled water into a coffee machine, be it espresso or a drip one, increases the risk of corrosion of the internal metal parts.
On top of that, some coffee makers, like Keurig, have water reservoir sensors that detect the mineral content in water.
Since there are no dissolved minerals in distilled water, the coffee maker won’t realize that you’ve already filled its water reservoir and won’t start its brewing cycle.
This was the quick answer, but if you want to get a deeper understanding of why not to use distilled water for making coffee, then continue reading.
Coffee Brewing with Distilled Water: Effect on Flavor
Coffee is up to 99% water, so the latter has a great impact on the flavor of your cup. Furthermore, it’s not only a fundamental ingredient, but also a solvent, and its composition influences the coffee taste and nutrient extraction.
As stated in this scientific report, the process of extraction of the flavor compounds of coffee depends on the dissolved mineral content of the water.
To explain why distilled water is typically bad for coffee from an extraction perspective, I need to go over the basics of water chemistry.
In nature, water contains dissolved salts, buffers, nutrients, etc. Their concentrations depend on the local conditions.
- pH – a measure of whether the water is acid, base or neither (neutral).
A pH of 7 is considered neutral, a pH below 7 – “acidic”, and pH above 7 is “basic” or “alkaline”.
Pure distilled water is neutral in theory (pH=7). Nevertheless, it’s highly reactive and as soon as it comes in contact with the atmosphere it starts absorbing carbon dioxide, which turns it acidic, with a pH value that is often below 6. - Buffering capacity is the ability of the water to maintain a stable pH when bases or acids are added to it.
Most of the water’s buffering capacity is ascribed to its carbonates and bicarbonates.
Often the terms “carbonate hardness” (KH), “alkalinity”, and “buffering capacity” are used interchangeably.
If you add acid to water with high alkalinity (i.e. KH), its high buffering capacity will absorb and neutralize the added acid without significantly changing the pH value.
Coffee is acidic, so if your water has a buffering capacity that’s too low, your cup will likely turn out too sour.
Contrarily, if the water KH is too high, the coffee will lack complexity and will turn out dull and unexciting. - General hardness (GH) is the measure of the concentration of magnesium and calcium ions.
GH is usually measured in parts per million (ppm) or milligram per liter (mg/l).
For example, water with general hardness of between 0 to 70 ppm is considered very soft, with 70 to 140 – soft, and from 140 to 210 ppm – medium-hard.
Calcium and magnesium ions help the coffee flavors go into the solution, so they’re essential if you’re looking for excellent results in terms of taste.
Nevertheless, you shouldn’t use water that is too hard, as your coffee will turn out somewhat bland and overall – lacking.
Furthermore, the heating of hard water in a coffee maker/espresso machine causes the precipitation of minerals, or in other words, the formation of limescale.
The harder the water – the higher the pace at which mineral deposits build up, which may cause machine malfunction, so you’ll need to descale it more often.
Related Post: Best Coffee Maker Descalers - Total Dissolved Solids (TDS) is a measure that gives information on the total concentration of dissolved substances in water – minerals, salts, metals, cations, or anions, etc.
TDS is often mentioned when discussing the optimal water parameters for brewing coffee.
Nevertheless, the TDS values aren’t quite helpful in this context, as they don’t tell us what the dissolved solids actually are.
Without this information, we can’t tell whether we’re using the best water for our coffee beans.
Now that you know the basics, let’s see what distilled water actually is.
The process of distillation involves boiling water, turning it into steam, and then cooling it down to become liquid again (condensation).
When the water evaporates it leaves behind all the solids that were originally dissolved in it.
After the condensation you end up with distilled water, that virtually has no minerals and contaminants whatsoever.
Distilled water has the lowest TDS, GH, and KH of all types of water. Its dissolved minerals are no more than 1 mg per liter (1 ppm), which means that this type of water is extremely soft.
Since distilled water has no buffering capacity, if you use it for brewing coffee, your brew will likely turn out harshly acidic. Furthermore, because of the lack of magnesium and calcium ions, the flavor compounds won’t get properly extracted.
Therefore you’ll likely be disappointed with the flavor of coffee made with distilled water, be it espresso, filter coffee, or, say, cold brew.
Using tap water is also not ideal, as it’s often too hard and at times – has an unpleasant chlorine flavor.
You could make improvements in your coffee if you use a filter pitcher to treat your tap water before brewing.
Nevertheless, if your tap water is too hard, this type of filtration may not reduce the mineral content sufficiently.
I’ll have a detailed post on the best water for coffee, where you can see all beginner-friendly guidelines on the type of water you should use to make an exceptionally good cup of Joe.
To be fair, there is no such thing as ideal water for all types of coffee beans.
For example, certain water parameters may be perfect for lightly roasted Ethiopian beans, but not for medium roasted Colombian beans.
Nevertheless, if you’re interested in improving your coffee by looking into your water’s chemistry, you can use the Specialty Coffee Association’s standards on water quality as a basic guideline.
| Characteristic: | Target: | Acceptable Range: |
|---|---|---|
| Odor | Odor-free/Fresh | |
| Chlorine | – | – |
| Calcium Hardness | 50 to 175 ppm CaCO3 | 50 to 175 ppm CaCO3 |
| Alkalinity | 40 ppm | 40 to 70 ppm |
| pH | 7 | 6 to 8 |
To test your water’s general hardness and carbonate hardness, you can use this API Test Kit.
Another thing that’s worth noting is that using distilled water for making coffee is a great idea if you remineralize it.
To do so you can use mineral packets, such as these by Third Wave Water, or craft your own “water for coffee” recipe by dissolving Epsom salt and baking soda into distilled water.
Author’s Note: During my research, I came across an intriguing study, investigating the effect of water hardness on the composition of coffee and its preference by university students.
As I would expect, the caffeine and chlorogenic acid contents were highest in the samples, made with distilled water.
What actually surprised me was that most participants in the study preferred the coffee, prepared with distilled water.
I decided to include this information, as a piece of evidence that in the world of coffee there are no strict rules.
So if you’re curious, try making a cup with distilled water. I totally would make a cup in my V60 as soon as I get the chance.
Nevertheless, I’d never add pure distilled water to my espresso machine’s water reservoir.
To find out why is that, read the following section of this post.
Why Isn’t Distilled Water Safe for my Coffee Maker
The internal parts of espresso machines and coffee makers are usually made of stainless steel, copper, brass, nickel, etc., all of which are metallic minerals.
Because of its chemical composition (i.e. lack of minerals), distilled water attracts metal ions from the internal components of your coffee maker/espresso machine.
You should avoid using pure distilled water, as it will lead to a slow breakdown of the metal parts of your coffee maker.
Furthermore, as previously mentioned, many coffee brewing appliances can’t detect water if it has no dissolved minerals in it.
So it’s safe to say that you shouldn’t use distilled water in your coffee maker or espresso machine, as this way you will avoid a malfunction or a higher risk of damaging it.
Still, if you’re determined to try a cup of coffee, made with distilled water, do your experiment by preparing it with a pour-over dripper or brew a batch of cold brew.
Final Words
I hope that you found my post informative and helpful and now you have a better understanding of why not to use distilled water for your homemade coffee.
If your tap water is too hard, but you don’t want to spend too much time and precisely measure your water parameters, I recommend using a mix of distilled water and tap water in a 1:1 ratio. Using bottled water with appropriate mineral content is also an option.
Share your thoughts and questions in the comment section below!
Your paragraph “Why Isn’t Distilled Water Safe for my Coffee Maker” doesn’t make sense. You say that distilled water will “attract metal ions”. What do you mean by that?
Distilled water is pH-neutral, and sure, any metal more reactive than hydrogen could potentially react with water and liberate hydrogen gas. But only magnesium and more reactive metals will react in cold or hot water. These are not used in the piping of such machines. Beryllium and aluminium could react with steam, but coffee machines do not get that hot, and are neither used. Less reactive metals, from titanium to lead, including iron, will react with steam (not hot water), but poorly. In other words, it is unlikely that you will have hot distilled water corroding the internals of your machine.
In fact, by using tap or filtered water, you are going to leave limescale in your machine, which will need to be cleared off with a descaling agent. Descaling agents are acids, usually citric acid, and they much more damaging to your machine compared to distilled water simply due to the pH level. Metals that won’t be attacked by hot water will be affected by hot acidic solutions.
In conclusion, I do not understand the rationale or reasoning, chemical or physical otherwise, behind your recommendation not to use distilled water. If you think I am mistaken or otherwise, please substantiate it with science and research and not opinions please. Many other authors online are saying the same thing without substantiation. That doesn’t make it true, but mere superstition.
The main reason I can think of using tap water over distilled water is cost. It takes a lot of energy to distill water. Unless you have a source of waste heat, making distilled water directly from the plug can make a significant dent on your electricity bills — about 0.85kWh per litre (or about 35 fluid ounces).
I drink distilled water almost exclusively including my coffee. It tastes great, my machine works fine and the coffee is excellent. Just say’n!
My sister is allergic to something in tap water so we have used distillled water in everything especially my coffee an it is great
I’ve been using distilled water for over a year. Coffee tastes better and my coffee machine is fins.
Hey Chris, thanks for sharing your experience! I’ve heard about people who’ve been using distilled water in their coffee makers without experiencing any negative consequences. I wouldn’t use it for my espresso machine though, as I’ve read a bit too much on this topic and I’m just too scared that it may damage it. When it comes to flavor, I guess it all comes down to personal preference. Thanks again for leaving a comment, I’m sure that it will be helpful for other readers too.