Water for Coffee Extraction

A pdf version of this blog post is available here.


In my first post, I mentioned how the water you use to extract coffee has a significant impact on the taste profile of your cup, in a way that does not necessarily depend on the taste of the water by itself. If you were using water just to dilute a cup of espresso (e.g., when making an americano), then your only worry would be that the water tastes good.

The key difference comes when you use water to extract coffee from the ground beans. In that situation, you want to have some potent mineral ions like magnesium (Mg+2) and calcium (Ca+2) that can travel inside the bean’s cellulose walls and come back with all the compounds that give the great taste to a cup of coffee. According to the Specialty Coffee Association (SCA), sodium (Na+) also plays a role, but a somewhat less important one. If you are wondering whether this is also true about tea – yes it is. If you live in Montreal, you might have noticed that you are unable to brew tea as good as the one you can drink at Camellia Sinensis, and your tap water is one main reason (they use mineralized water at Camellia Sinensis).

The Recommended Water Properties

In this post, I’d like to discuss extraction water a bit more, and give some practical tools for everyone to improve their brew water without necessarily needing fancy equipment. Let’s start by listing some of the SCA recommendations for brew water (I ordered them in my perceived order of importance):

  • No chlorine or bad smell
  • Clear color
  • Total alkalinity at or near 40 ppm as CaCO3
  • Calcium at 68 ppm as CaCO3 , or between 17–85 ppm as CaCO3
  • pH near 7, or between 6.5–7.5
  • Sodium at or near 10 mg/L
  • Total Dissolved Solids (TDS) at 150 mg/L, or between 75–250 mg/L

The first two are more widely known, but it’s always good to keep in mind if you start creating your own mineral recipes (more on that later). If your resulting water is milky or has visible precipitation of minerals, it’s not good ! If this happens, you probably added way too much minerals for some reason. You can also easily get rid of chlorine by letting water sit on the counter for an hour or so.

Total alkalinity is often confounded with pH, but it’s not the same thing. pH measures the (logarithm) ratio of free OH ions to H+ ions in a solution, with pH = 7 corresponding to a unit ratio (neutral). A larger amount of H+ ions produces a more acidic solution, with a lower pH, and a larger amount of OH ions produces a more alkaline solution, with a higher pH. This is why total alkalinity is often confused with an alkaline solution, which is kind of understandable given this poor choice of terms.

Total alkalinity typically measures the amount of HCO3 ions, which are able to capture any free H+ ions that are added to the solution, and prevent them from making the solution more acidic by forming carbonic acid: 

For this reason, HCO3 is termed an alkaline buffer in this context. A high total alkalinity will therefore make a solution more stable against pH changes. This bears some importance in coffee making, but there is a big problem with having a total alkalinity that is too high; it can react with the aromatic acids that were extracted from the coffee beans, and mask some of these important flavors. This is why the SCA recommends a very narrow range in total alkalinity near 40 ppm as CaCO3.

You may sometimes hear total alkalinity referred to as carbonate hardness. It’s a slightly different concept, but for coffee extraction water it’s almost always equal to total alkalinity (technically, this is true when the total hardness of water is higher than its total alkalinity).

At this point you may thinking “what the hell is this unit of measurement involving this random molecule CaCO3 ?”. Turns out scientists love to create large collections of weird measurement units, and this is yet another example of that (like measuring the energy of stars in ergs…). These ppm as CaCO3 basically ask “how many parts per million CaCO3 would you need to produce the observed HCO3 concentration ?”, which relates to this chemical reaction: 

The next recommendation is to have calcium hardness between 17–85 ppm as CaCO3, with the units again relating to the same chemical reaction above. Magnesium is also widely used in the specialty coffee association, and is believed to extract slightly different flavors, but to my knowledge there are not yet any lab tests to back this up (there might be some blind testing backing it up, but I’m not aware of them). As a consequence, most people use a mix of magnesium and calcium as the extracting agents. I already explained the logic behind this recommendation above; you basically just want enough of these cations to do the extraction job properly, but not too much as to completely throw off balance the flavor of the coffee or to cause massive corrosion or scaling in your equipment.

Both of the magnesium and calcium cations are related to the total hardness of a solution, defined as the summed concentration of many cations (positively charged ions), among them calcium, magnesium, iron, strontium and barium. In coffee extraction applications, only magnesium and calcium are typically present, so total hardness is just taken as their sum. A more widely used recommendation would therefore be to keep total hardness in the SCA range, rather than just calcium hardness.

The next two recommendations are often not focused on too much in the specialty coffee community. I often see water recipes with pH in the range 8.0–8.2 (slightly alkaline), and the resulting coffee tasted great. I haven’t done extensive tests comparing pH~7 water to these recipes, as it’s typically hard to play with pH without affecting the other variables above. I also have not experimented much with the effect of sodium, so that could be the subject of a future blog post; for now, I just try to follow the SCA recommendation, but I don’t put too much focus on it.

A lot of people use tap water through a Brita to brew coffee. This is not bad in principle, but all such a carbon filter does is remove chlorine and other undesirable components, and soften the water (it decreases total hardness and total alkalinity). If this lands you in a good zone for brewing, that’s great, but it is rarely the case for typical tap water.

Visualizing the Water Options

At this point, it would be useful to visualize the water properties of different cities, bottled waters and some recipes of coffee professionals: 

Water properties for various recipes, cities and bottles. The dashed line represents a 1:1 relation, and color lines correspond to different recommended ranges.

In the figure above, you can see the range recommended by the SCA (green bar), the region recommended by the Colonna-Dashwood & Hendon (2015) Water for Coffee book (this mythical book is now pretty much impossible to find, but it is said by the ancient ones to go much deeper in the chemistry of coffee extraction than what I could ever write in this blog post), and the more constrained region recommended by the Specialty Coffee Association of Europe (SCAE), which is mainly based on avoiding regions of significant scaling (upper right) or corrosion (upper left), two aspects that are mostly important to the delicate internal parts of espresso machines. The Third Wave Water (TWW) classic and espresso profiles are little bags of pre-weighted minerals that you can dump in a gallon of distilled water to get easy water for coffee brewing.

The dashed line on the figure corresponds to a 1:1 total alkalinity and total hardness. Most naturally occurring water will fall near this line because of how water acquires its minerals by dissolving limestone. The widely used process of water softening by de-carbonization also moves the composition along this region (toward the origin of the figure). This is why a lot of city tap waters (triangles) and bottled waters (stars) fall along that line. I can’t believe that I lived for 3 years in Washington D.C. without ever knowing about any of this (and I Brita’d my water out of this great spot like a fool). You would be surprised how many of the city or bottled waters that fall completely outside of the range of this figure.

All other circles on the figure correspond to mineral recipes used or recommended by different professionals (e.g.,  the Leeb & Rogalla book, Scott Rao, Matt Perger, Dan Eils, the World of Coffee Budapest championship, the 2013 Melbourne World Barista Championship, and several recipes from Barista Hustle), the stars correspond to bottled waters, and the triangles correspond to different cities.

Practical Implementations

Now that we talked about the theory behind extraction water, we should focus on practical applications. You would be surprised how many specialty coffee shops have very expensive water filtration systems based on reverse-osmosis to rid the water of all its contents, and re-mineralization resins to achieve something close to these recommendations (try asking your favorite coffee shop).

At home however, none of this is really practical, as these devices typically cost several thousands of dollars, and still require you to monitor your tap water and adjust their setting from time to time. Unless you have the incredible luck of living somewhere with great brew water (the only example I know is Washington DC, at least in 2018), you have these types of choices (ordered by increasing effort required):

  • Get a magnesium re-mineralizing water pitcher (e.g., the BWT).
  • Order some third wave water minerals and dissolve them in a gallon of distilled water.
  • Mix a pre-determined combination of bottled water brands.
  • Buy distilled water and re-mineralize it yourself. This requires a bit more work but gives you incredible flexibility.

The BWT Pitcher

The first option has the merit of being simple, but you have almost no control over the final result. A BWT pitcher will soften your water and then add in some magnesium, which will move you toward (0,0) and then upward in the figure above. I don’t know to what extend it moves the composition around, so ideally you’ll want to test the result with some aquarium water hardness and alkalinity kits. I suspect the result would be decent in cities with similar compositions to Montreal.

Third Wave Water

I found that third wave water (the “classical profile”) produces a really good result for very little effort. You do have to buy a gallon of distilled water, which is a bit of effort, but they are extremely cheap and will last for a dozen cups of coffee. The “espresso profile” of third wave water is useful if you are worried about scaling and corrosion in your espresso machine, so I recommend only using it for espresso, not for filter coffee. I compared a Colombian coffee (the Ignacio Quintero from Café Saint-Henri) extracted with third wave water, the Rao/Perger and Dan Eils water recipes (discussed more below) by blind tasting, and I found the third wave water to be a bit overwhelming in term of resulting acidity.

My guess is that this is due to third wave water being much higher than the other recipes in terms of total water hardness. I preferred the Rao/Perger recipe, but in all honesty all three cups were very good, and way better than what you get with Montreal tap water. I think third wave water is also a good option for traveling, as it comes in a little sealed package with the composition marked on it, so that might not cause problems at TSA (although I have not tested this yet). You would still need to buy a gallon of distilled water though, so depending on the nature of your trip this could be a non-ideal solution.

I must confess, I am not sure I placed the Third Wave Water points on the right position of the “total alkalinity” axis. This is because they use a less usual component called “calcium citrate”, or Ca3(C6H5O7)2 in their mix of minerals. Once dissolved in water, each of these molecules will liberate three Ca+2 cations and two C6H5O7-3 citrate anions (negatively charged ions). I treated each of these citrate anions as an alkaline buffer that can capture three H+ cations each, and assumed that they are stable enough as citrate acid (C6H8O7) to prevent a significant pH change. This is a lot of assumptions, and I also needed to assume that citrate acid is as efficient at actually capturing the H+ cations as are the HCO3 anions. Once I made these assumptions, I just calculated what amount “ppm as CaCO3” of HCO3 would have the ability to capture the same amount of H+ cations. It is quite interesting that the classic profile falls quite close to other brew water recipes in total alkalinity when making all these assumptions.

[Update, January 3 2019: I have now tested the total alkalinity of Third Wave Water (classic profile) with a Hanna Instruments photometer, and obtained a measurement of  43 +/- 5 ppm as CaCO3 total alkalinity; this is very close to the ~ 50 ppm as CaCO3 that I had predicted ! It could be slightly lower because citrate anions may be slightly slower or worse at capturing H+ cations, but this is almost within the measurement error so I would not deduce too much from this measurement alone. The main point is: citrate anions do act as an alkaline buffer, and third wave water is exactly at the SCA-recommended value for total alkalinity !]

Water properties for various bottles. The dashed line represents a 1:1 relation, and color lines correspond to different recommended ranges. Orange dashed lines show all possible combinations of Montclair/Distilled or Compliments/Distilled ratios, and stars A, B and C represent the corresponding water bottle recipes described in the text.

Bottled Water

Mixing water bottles or distilled water is another viable option. If you use a combination of two bottled waters, you can imagine a line drawn between the two stars that correspond to each of the bottled water properties in the figure above, and different mixing ratios will place you at different spots along that line. Using three bottled waters instead of two will allow you to move on a triangle-shaped surface that connects the three bottles in the chart. A problem with a lot of bottled waters is that they are not far above the 1:1 total alkalinity vs total hardness line (the dashed line in the chart), making it harder to fall anywhere in the Colonna-Dashwood & Hendon (2015) region. The lack of bottled waters high in total hardness and low in total alkalinity limits the use of three-bottled combinations.

From the little data gathering I have done yet, I found that using a water really high in both total alkalinity and total hardness (like Montclair water) mixed with much softer water is a good way to go. Here are a three bottled water recipes that seem to work great (with their designated letter on the next figure):

(A) The Montclair/Smart recipe

Right now, the best 2-bottled combination I could find is 10 parts Smart Water to 1.6 parts Montclair. This will place you at a total alkalinity of 40 ppm as CaCO3, and a total hardness of 69 ppm as CaCO3, nicely split between calcium (17 mg/L) and magnesium (6 mg/L). It will even include 5 mg/L of sodium, falling a bit short but not that far from the SCA recommendation.

(B) The Montclair/Distilled recipe

Another great option is to mix 10 parts distilled water with 2.05 parts Montclair water. This is very similar to the last recipe, but slightly softer (67 ppm as CaCO3), and with a bit more sodium (9 mg/L), extremely close to the SCA recommendation in sodium.

(C) The Smart/Compliments recipe

If you can’t get your hands on Montclair water, try this one: 10 parts Smart Water with 1.6 parts Compliments. This will get you something a bit softer in total hardness (57 ppm as CaCO3), still with a mix of calcium (14 mg/L) and magnesium (5 mg/L), but without sodium. 

I have not tried tastings with these bottled water recipes yet; this was determined just from calculations. Let me know if you try them before I do !

If you would like to experiment with some more mixes of bottled water, I created a Google Sheet here, which I will keep updating in the future. You can do File/“Make a Copy”, and then you’ll be able to add in some more bottled water and create new recipes. You can also find many more mixed bottle water recipes that I fiddled with in there.

Another viable option may be to mix your tap water with distilled water, but this will only allow you to move along a line connecting (0,0) to your city in the first figure, and you would ideally need to monitor seasonal variations in your tap water hardness and alkalinity. I added a few tap water compositions (Montreal, Laval and Washington DC) in the bottled water spreadsheet.

Mineral Recipes

If you want to take things to the next level, you can get yourself some minerals, a scale precise at 0.1 g or better (mg-precision scales are not too expensive; I use this one and I really like the small plastic dishes that come with it), some mason jars, and a pipette or a small kitchen plastic spoon. There are a total of five minerals you will need if you want to do all of the recipes below, but the simpler ones can be done with just the first two in this list. For the less common items, below I will give you some Amazon links that I used to buy them.

Please make sure you always buy food-grade ingredients, not the pharmacy-grade or lab-grade ones. The latter two may be more pure than food grade is, but the rare impurity could be much worse for your health (e.g., heavy metals). Barista Hustle mention that pharmacy-grade epsom salt is probably ok to consume at these low concentrations, but I consider the key word here to be “probably”, especially if you’re going to drink this every morning. Once you opened a bag of minerals, always keep them in a cool, dry place in a hermetic jar, especially those in anhydrous form.

    • Epsom salt (MgSO4•7H2O) [Amazon]
    • Baking soda (NaHCO3) – This is not baking powder. [Amazon]
    • Magnesium chloride hexahydrate (MgCl2•6H2O) [Amazon]
    • Calcium chloride anhydrous (CaCl2) [Amazon]
    • Bicarbonate potassium (KHCO3) [Amazon]

Notice that epsom salt is not simply MgSO4, but rather its heptahydrate form MgSO4•7H2O, which makes it look like a clear crystal. MgCl2 and CaCl2 can be found both as hydrates or anhydrous (no water) forms. Some vendors don’t specify what form they are providing, which can be annoying, but in general if you have little white spheres of CaCl2 they are probably anhydrous, and if you have milky clear crystals of MgCl2 they are probably of the hexahydrate from (see pictures below). It’s ok if you don’t get the exact hydrate form, but you’ll need to adjust the weights to get the same amount of Ca+2 or Mg+2 cations. 

Anhydrous CaCl2 (top) and hexahydrate MgCl2 (bottom). The pale, milky crystalline structure is a good indication that you have a hydrate form of MgCl2.

After doing some research on the web, I could get my hands on a dozen mineral water recipes. I have not tried them all yet, but I will comment those that I did try. I modified all recipes below to make them more uniform. In all cases, you’ll need to put the specified weights of minerals in a jar that can hold 200 mL of water (ideally slightly more). A glass jar such as a regular mason jar is good for this, and I would avoid metallic containers because of potential corrosion.

Once you put the required minerals in the jar, add in some distilled water until you hit a total weight of 200 g. This will be your concentrate; a solution often white that will initially degas some CO2 and will easily precipitate solid minerals. I recommend keeping such a concentrate in a cool dark place for a few hours with the mason jar lid just slightly screwed, to allow for the outgassing to complete. You might even stir it up a few times to help things get going. You will also get a much faster reaction and outgassing if you use warm or hot distilled water, but I am not sure if this affects the resulting composition (I don’t think it does, and my first trial with the Rao/Perger recipe and hot distilled water turned out great).

Your concentrate will be good for 50 liters of water. This is a lot of water. Think of it like this: you can fill a very big bath with amazing coffee with that much water. In other words, I highly recommend (1) not going crazy and starting up 8 different 200 mL concentrates when you first read this, and (2) keep them tightly closed in the fridge after they degassed. If you want to compare several water recipes, you can create downsized versions of the concentrates without problem (use a rule of three to downsize both the concentrate volume and mineral weights by the same factor).

Once you have a concentrate, I recommend putting it on your scale, taring the scale, and using the pipette or small plastic spoon to scoop out 16 g and put it in a 4 L of distilled water (or 4 grams per liter). Congratulations, this is your mighty brew water. Make sure you keep it in the fridge, especially when it is almost empty, and always smell it before using it. As I mentioned in my last post, if it smells like an old rag, so will your coffee. In my experience, a gallon of distilled water will turn bad after approximately a week out of the fridge, or a month in the fridge. This is a much slower staling process than what you would get with tap water, as distilled water starts out free of any bacteria. I also don’t really recommend letting the water sit in your boiler for more than a few hours, but this is definitely less an issue when you started with distilled water as a base.

Now, here are the recipes !

The Rao/Perger Recipe

    • 5 g epsom salt (MgSO4•7H2O)
    • 2 g MgCl2•6H2O (hexahydrate) or 1 g anhydrous MgCl2
    • 1.5 g anhydrous CaCl2 or 2 g CaCl2•2H2O (dihydrate)
    • 1.7 g baking soda (NaHCO3)
    • 2 g bicarbonate potassium (KHCO3)

Reference: Scott Rao

Comments: So far this is my favorite recipe from blind testing.
It produces a bright and well-balanced cup.

[Edit May 11, 2019: Please note that this concentrate (and perhaps others on this page) will precipitate some white salts. This is perfectly normal and it will not precipitate once diluted with distilled water into your brew water. Just make sure that you mix the concentrate thoroughly until no deposit is left at the bottom every time before you use it.]

The Dan Eils Recipe

    • 5 g MgCl2•6H2O (hexahydrate) or 2.3 g anhydrous MgCl2
    • 3.8 g anhydrous CaCl2 or 5 g CaCl2•2H2O (dihydrate)
    • 5 g bicarbonate potassium (KHCO3)

Reference: Scott Rao’s Instagram post

Comments: This is a great and simple recipe.
So far, my 2nd best favorite from blind testing.

The Matt Perger Recipe

    • 10 g epsom salt (MgSO4•7H2O)
    • 3.4 g baking soda (NaHCO3)

Reference: This website.

Comments: I have not tried this one yet.

The Rao 2013 Recipe

    • 4 g MgCl2•6H2O (hexahydrate) or 1.9 g anhydrous MgCl2
    • 3 g anhydrous CaCl2 or 4 g CaCl2•2H2O (dihydrate)
    • 3.4 g baking soda (NaHCO3)

Reference: I deduced this one from other recipes above.

Comments: I have not tried this one yet.

The Melbourne Recipe

    • 2.9 g epsom salt (MgSO4•7H2O)
    • 1.0 g baking soda (NaHCO3)

Reference: The Barista Hustle simple DIY recipes.

Comments: I have not tried this one yet.

The World of Coffee Budapest Recipe

    • 6.2 g epsom salt (MgSO4•7H2O)
    • 3.4 g baking soda (NaHCO3)

Reference: The Barista Hustle simple DIY recipes.

Comments: I have not tried this one yet.

The Barista Hustle-Simplified SCA Optimal Recipe

    • 8.4 g epsom salt (MgSO4•7H2O)
    • 3.4 g baking soda (NaHCO3)

Reference: The Barista Hustle simple DIY recipes.

Comments: I have not tried this one yet.

The Barista Hustle Recipe

    • 9.8 g epsom salt (MgSO4•7H2O)
    • 3.4 g baking soda (NaHCO3)

Reference: The Barista Hustle simple DIY recipes.

Comments: I have not tried this one yet.

The Barista Hustle-Simplified Rao 2008 Recipe

    • 9.2 g epsom salt (MgSO4•7H2O)
    • 4.2 g baking soda (NaHCO3)

Reference: The Barista Hustle simple DIY recipes.

Comments: I have not tried this one yet.

The Barista Hustle-Simplified Hendon Recipe

    • 12.2 g epsom salt (MgSO4•7H2O)
    • 2.6 g baking soda (NaHCO3)

Reference: The Barista Hustle simple DIY recipes.

Comments: I have not tried this one yet.

The Barista Hustle Hard Recipe

    • 15.4 g epsom salt (MgSO4•7H2O)
    • 2.9 g baking soda (NaHCO3)

Reference: The Barista Hustle simple DIY recipes.

Comments: I have not tried this one yet.

The Barista Hustle Hard “AF” Recipe (i.e., “Hard as Falcon”)

    • 21.5 g epsom salt (MgSO4•7H2O)
    • 3.8 g baking soda (NaHCO3)

Reference: The Barista Hustle simple DIY recipes.

Comments: I have not tried this one yet.

I also collated all of these recipes in another Google sheet, which you can also play with if you do File/“Make a Copy”. That one will estimate the resulting total hardness and alkalinity from the input recipes, as well as other detailed quantities. You can also use the Aqion website to get the same outputs for the simpler recipes (maximum 3 minerals, and the calcium citrate present in Third Wave Water cannot be included). A nice aspect of the Aqion website is that it also gives you the electric conductivity (EC), in the units of μS/cm (microSievens per centimeter) often measured by cheap TDS-meters (TDS is for total dissolved solids). This is a great way to double-check that you didn’t mess up your brew water, but always make sure you measure it at 25°C. Even when TDS-meters say they do a temperature correction, it’s a bad one. I would also not trust the TDS reading itself, because these instruments make important assumptions on the actual composition of your water to translate the EC to a TDS.

Happy brewing ! In BOTH senses 😀

Special thanks to Alex Levitt and fungushumungous for proofreading.


43 Replies to “Water for Coffee Extraction”

  1. Wow… I read it quickly, and I definitely will read it again with more time… I just tried out the BH simple receipts with epsom + baking soda. But to be fair, I ended up with TWW for my first brewing competition.
    But as a science geek: I HAVE to go deeper into that 🙂
    Thanks for sharing!


  2. So for making a recipe…is the required measurements added to 200g of total water or is it 200g total weight including the minerals?


      1. So after a few days of making the concentrate I am noticing white flakes floating around and they don’t seem to dissolve after shaking. Did I do something wrong? (I did your Matt Perger recipe)


      2. I don’t think this is normal, no. Did you put 10g epsom salt and 3.4g baking soda with 186.6 g distilled water to get your 200 g concentrate ? How long did you wait for the concentrate to react ? To obtain your brew water, did you put 4 grams of the concentrate per litre of distilled water and not more ?


  3. I did exactly what you just said. I waited overnight for it to react with the cap barely screwed on. I never refrigerated it though. Could this be the reason?


    1. Refrigeration is only useful if you keep your concentrate for months, so this is not the issue. What kind of epsom salt and baking soda did you use exactly ? If you could post links to images that could help.


    1. These look good – I think it may have more to do with using a clean bottle yes. If you try again in a cleaner bottle you shouldn’t see this. Also this could have messed up the total alkalinity of your brew water.


      1. Hi,Jonathan
        I have tried the first recipe, The Rao/Perger Recipe, about 5 hours ago, with 200g hot distilled water. And I think I have the same problem like Scott Lotosky dose. The minerals are floating in the water if I shake(or stir)the bottle,looks like a glass of diluted milk.

        Here is another question. My tap-water is GH=17ppm KH=15ppm, if I want to make brew water with my tap-water and after the first recipe, should I reduse some minerals? Like skip the NaHCO3?



      2. Hi Zhu Hao, it is normal that the 200g concentrate is white with some mineral deposits. Once you put 4g of it per liter in distilled water to obtain your brew water, then the brew water should be clear and transparent.

        If you want to create brew water from your tap water, you will need it to be very soft, and yes you will need to reduce the mineral content. Send me an email through the contact form and we can figure out the exact concentration you would need. If you happen to know how much Mg versus Ca there is in your tap water, that would be useful.


  4. Okay I will redo it. My coffee actually tasted pretty good but maybe it could be even better. Thanks! I will let you know how it goes.


  5. If this question is too obvious or foolish to respond to I understand. But . . . I really like my local spring water for regular drinking. Rather than buy yet more water with disposable plastic containers, I’d rather tweak my spring water. But so far, and for good reason, mostly coffee manipulated water seems to be based on a recipe added to distilled water. If I want to shape the taste of my spring water for espresso (Decent) and brew (Hario syphon), how might I proceed? My spring water, for instance, has a Ph of 7.8, Hardness of 51.3, Total Alkalinity of 40, and TDS of 38. and although I know what Rao and others recommend, my complete lack of chemistry knowledge leaves me unable to figure out what to add in and in what quantities to bring my spring water into a more desirable range. Any suggestions or links to articles that might be of aid would be greatly appreciated.


    1. Hey Roger, that’s a really good question. Nothing wrong with minimizing waste.

      You’re very lucky that your spring water is at a total alkalinity of 40 ppm as CaCO3, that’s very similar to my favorite recipe. Please double-check that your units are “ppm as CaCO3” with the test you made, to be sure we’re comparing apples to apples. Also, please check that your total hardness is also expressed with “ppm as CaCO3”. Do you happen to know how much of your total hardness is composed of calcium vs magnesium ? If we happen to know, then we can reproduce my favorite recipe exactly. Also, it would be good to use something like a TDS-meter to monitor your spring water from day to day, just to make sure it doesn’t change too much.

      Otherwise, here’s how I would reproduce the Rao/Perger water recipe by starting from your spring water, assuming its hardness is all calcium (I think it’s more common than magnesium in spring water). The Rao/Perger recipe has a total hardness of 87.5 ppm as CaCO3, so we’ll add 36.2 ppm as CaCO3 magnesium to your water.

      To do this, you’ll need distilled water for your concentrate – don’t worry, it will last you for countless litres of actual brew water. You’ll also need magnesium chloride (MgCl2). If you have the crystallized version (it’s called hexahydrate MgCl2, and is the most common one), weigh 5.2 grams of it (use a scale precise at 0.1 grams or better) and put it in a >1.5 L jar, ideally a plastic or glass one with a plastic lid (your concentrate will be somewhat corrosive). Boil some distilled water. Put your jar of MgCl2 on your scale and tare it. Top it off with boiling distilled water until you have a solution that weighs 1500 g in total. Shake it well, and don’t close it in case it degases (I think it shouldn’t). After an hour or so, close it tightly and store it in the fridge. This is your concentrate, not your brew water ! You can keep this in the fridge for a long time, because you started it from distilled water, and the high mineral concentration will make it hard for bacteria to grow in it (any bacteria will explode in contact with that concentration of minerals by osmosis).

      What you’ll do after this is add 10 grams per liter of this concentrate to your spring water, and you should end up with the same total hardness as the Rao/Perger recipe (feel free to test it !). You can either keep your spring water always in the same plastic container (make sure it’s in the fridge, and wash it thoroughly with warm soap every few weeks) and add 10g/L of concentrated water to that container, or add the appropriate amount of concentrate every time you brew, directly in your kettle. If you do the latter, I’d add the concentrate to warm or boiling water and immediately shake it well so that it dissolves as fast as possible and doesn’t corrode the metal of your kettle. Another option would be to combine the spring water & minerals it in a plastic container, shake it well and then pour it in the kettle. If you know your exact calcium or magnesium concentration, would like a different size of concentrate, or don’t have this particular form of MgCl2, don’t hesitate to comment again and I can help you. If you store brew water in the fridge, always smell it before using it – you’ll be more susceptible to bacterial build-up because you don’t start from distilled water. But if there’s a problem, you’ll smell it. I would not keep a given batch of your brew water outside the fridge for more than a few hours, or in the fridge for more than approx. a week.


  6. Hi Jonathan, very interesting blog you have here. Here are the tap water measurements of my town:

    Taste: none @14.5°C
    Colour: colourless
    Clarity: clear
    Smell: none @14.5°C
    Threshold odour number: TON 1 @23°C

    pH: 8.19 @14.5°C
    Total Hardness: 4.88°dH
    Calcium Hardness: n.a.
    Total Hardness in CaCO3: 0.9mmol/l
    Conductivity: 235μS/cm @14.5°C
    Conductivity: 212μS/cm @25°C
    Summ Anions: 2.39mval/l
    Summ Kations: 2.46mval/l
    Base Capacity Kb8.2: <0.1mmol/l
    Acid Capacity Ks4.3: 1.88mmol/l
    Oxygen: 10.5mg/l @14.5°C

    [Note: The Base Capacity is also called -p-value. It says how much mmol/l of Phenolphthalein must be added to a liquid to get a pH of 8.2. at a pH of 8.2 all carbonates have the oxidation state of ions.

    And the Acid Capacity is also called m-value. It says how much mmol/l of Methylorange must be added to a liquid to get a pH of 4.3. The higher this value is the more hydrogen carbonate is available in the water, which buffers acids.]

    Alkali metals (Group I in the periodic system):

    Lithium (Li+1): n.a.
    Sodium (Na+1): 14mg/l
    Potassium (K+1): 4.3mg/l
    Rubidium (Rb+1): n.a.
    Caesium (Cs+1): n.a.
    Francium (Fr+1): n.a.

    Alkaline earth metals (Group II in the periodic system):

    Beryllium (Be2+): n.a.
    Magnesium (Mg2+): 6mg/l
    Calcium (Ca2+): 25mg/l
    Strontium (Sr2+): n.a.
    Barium (Ba2+): n.a.
    Radium (Ra2+): n.a.

    Note: 1+/2+ is the normal oxidation state of this metals, which means they lost two electrons and got a positive charge which makes them to ions with a basic potential. (Correct me if I'm wrong.)]

    Fluorid (F-): 0.39mg/l
    Nitrat (NO3-): 1.4mg/l
    Chlorine (Ch-): 9.6mg/l
    Sulfate (SO42−): 13mg/l
    Oxygen(O2-): 10.5mg/l @14.5°C

    Let's see how close I am to the SCA water standard:

    Odor: Clean, Fresh, Odor free
    This fits my water quality.

    Color: Clear Color
    This also fits my water.

    Chlorine: 0mg/l
    Here I have too much chlorine (9.6mg/l)
    To remove it I should use a active carbon filter.

    Total Dissolved Solvents (TDS): between 75-250 mg/L TDS, with a target of 150.
    Here I have a Problem: The Institute hasn't measured this value, but there are TDS measuring devices for relative less money. There is also a Formula which includes the conductivity and a correlation factor which is between 0.55 and 0.8.
    The problem: I have no clue what the correlation factor of my water is.
    The formula says TDS = KE × EC
    TDS stays for the Total Dissolved Solids
    KE stays for the correlation factor and
    EC stays for the conductivity.
    e.G. That means for me If I use the conductivity of 235μS/cm @25°C and a correlation factor of 0.55-0.8 I'm in the range of 129.25-188TDS
    (Source: https://m.wikihow.com/Calculate-Total-Dissolved-Solids )

    Calcium Hardness: 1-5 grains per gallon (gpg) or 17-85 mg/L, with a target of 3-4 gpg or 51-68 mg/L.

    The Calcium Hardness or Total Hardness includes +2-Cations such as Calcium (25mg/l), Magnesium (6mg/l) Mangan and Iron (which are pretty low in my water at 0.003mg/l and 0.035mg/l, so they play no big role for the Total Hardness.

    For me that means my calcium Hardness is around 31mg/l, which is a little bit too less.

    On the protocol it says my calcium Hardness in Degree German Hardness °dH = 4.88
    25mg/l Calcium are 0.62378mmol/l or 3.498°dH
    6mg/l Magnesium are 0.24686mmol/l or 1.3843°dH
    3.498°dH + 1.3843°dH = 4.8843°dH

    Here is a very useful online calculator for water hardness: https://www.cactus2000.de/uk/unit/masswas.php

    Total Alkalinity: At or near 40 mg/L
    This is also not listed directly on the protocol, but I can calculate it from the Acid Capacity Ks4.3 (1.88mmol/l) by multiply it with the factor 2.8 = 5.264°dH. Just put that value into the hardness calculator and I get 93.952mg/l (or ppm)

    This shows that my water is really good at neutralizing the pH of coffee (which is between 4.9-5.1)

    To explain this on the sample of a V60-brew:
    If I pour my water over the grounds, the Calcium- and Magnesium-Hydrogencarbonates tries to neutralize the sour pH of the coffee and releases Carbonic Acid at the same time:

    Ca(HCO3)2 + C4H4O =CaH8C7O4 + H2CO3
    Mg(HCO3)2 + C4H4O = MgH8C704 + H2CO3
    The C4H4O (Furan, we smell it as caramel aroma in the coffee) is just one of the like 800 chemicals we can find in coffee, just to have an example for this formula. I also could be wrong with that. It's just a theory and I only got a basic education in physics at the middle school.

    Also many people's get confused with calcium Hardness which are higher than the total hardness.
    Even JBL who makes Carbonate Hardness test kits (which measures the alkalinity!) Thinks the carbonate Hardness can be higher than the Total Hardness because the Total Hardness only includes Calcium and Magnesium and the carbonate Hardness can have all sorts of minerals in them (e.G. Kalium, Natrium).
    The Carbonate Hardness says how many Calcium and Magnesium ions are bound to (Hydrogen)- carbonates (aka Temporary Hardness since if you bring water to boil Calcium- and Magnesium-Hydrogencarbonates will split into Calcium-/Magnesiumcarbonates (limescale) and CO2 (which leaves the boiling water)

    Temporary Hardness/Carbonate Hardness:
    Surprisingly I haven't found any recommended value for the Temporary Hardness in any book I own but it seems that the Deutscher Kaffeeverband ( German Coffee Association, not SCA Germany) recommends a KH of 3-4°dH for espresso.
    Since the Carbonate Hardness isn't listed in most water recommending charts I guess It has a greater effect on limestone than on taste.
    The water analysis institute hasn't measured it too, but there Is a formula I found on a German Bear brewers forum:

    KH [°dH] = (A x 21.8 – B – C – D – E) / 21.8

    KH = Karbonathärte
    A = GH [°dh] (Gesamthärte)
    B = mg/l Sulfat (SO42-)
    C = mg/l Chlorine (Cl-)
    D = mg/l Flourid (F-)
    E = mg/l Nitrate (NO3-)

    KH [°dH] = (4.88°dH x 21.8 – 13mg/l – 9.6mg/l – 0.39mg/l – 1.4mg/l) / 21,8
    KH [°dH] = 3,76°dH
    But I'm sceptical if this works like this since the total hardness doesn't includes any Cations I could subtract (but it seems that the peoples in the forum gets close results to their measurements)


    pH: 6.5-7.5, with a target of 7.
    I'm at 8.19. This leads to an overwhelming flat cup, but mine also gets sour mostly.

    So why is my water so alkaline? Maybe it has a high amount of hydroxide in it.

    So how can I lower the pH of my water? I could remove some basic anions such as Calcium, Magnesium and Sodium, but then my coffee still would taste pretty sour.

    I searched through aquaristic forums (because they know a lot about water science) and found that they use CO2-gas systems to higher the Co2-content in the water to lower the pH (and also the plants needs CO2 and light to turn the CO2 into C (which turns into sugar for the plants) and release O2 (which fish needs to breath).

    If you use a CO2-gas system in combination with a pH-controller you can controll the CO2-gas to keep the pH-value on a constant level.

    Sodium: Less than 30 ml/L, with a target of 10 mg/l
    Here I'm at a good value with my 14mg/l, also if it could be less.


    But for the start I just could use a Brita filter who gets rid of all the nasty minerals and softens my water and if the low mineral content makes my coffee tasting too sour I could place an Aquarium with CO2-gas system under my kitchen sink.

    It also would be interesting to find a Mineral-Profile for my tap-water, but it would be hard to decrease the pH. Maybe some citrus juice could help with that or do you know any good food-grade chemicals which doesn't effect the taste of my coffee to much (in a bad way) which lowers the pH?

    Oh, and there is also a water-recipe from Quaffe:


    And here I have some more interesting Links:


    (They say Magnesium emphasizes the natural sweetness in coffee, Calcium allows maximum extraction, Sodium enhances the complex taste profile of the coffee and fresh water has a good oxygen saturation and has a positive effect on the coffee taste.
    But there is no detailed explanation why this is so.)




    Somehow it's good that my water isn't perfect. It drives me nuts so I researched so much about it and I'm still not done with it.
    Cheers, Matthew.


    1. Hi Matthew, thanks for your comment. Lowering the pH of your water is not an easy task, you might need to change the alkaline buffer entirely. For now I craft my water from distilled water and I get pH around 7.5-8.2, ideally I’d want 7 but I’m not there yet. I’ll make a post on it for sure if I find out a way to get a neutral pH. It’s not clear to me how much it affects the taste of the coffee though, total alkalinity seems more important.


    2. PS if you add citrus juice to reduce your pH you will first completely rid your water of its total alkalinity (this is why it’s also called an alkaline buffer). That’s why I think changing the alkaline buffer to one that stabilizes near 7.0 would be needed.


  7. If I use a Mineral salt like any Magnesium- or Calcium-Salt, e.G. Magnesium Chloride (MgCl2),
    How do I calculate how much Magnesium and Calcium is in e.G. 1g of that Pulver in % or g/100g? Is there like a formula which includes the atomic or molar mass and density, or is It just taking the atomic mass of Calcium (40.078u) by 1 and the atomic mass of Chloride (35.45u) by 2 (= 70.9u) and get 36.11% Calcium and 63.89% Chlorine by my percentage formula, now using that on 10g MgCl²-pulver (3.611g Mg, 6.389g Cl), adding that to 200ml RO-water for my concentrate (resulting in 18.055g/l Mg, 31.945g Cl), taking 5g of my concentrate and adding it to 1l of brewing water ( 18055mg/l ÷ 1000ml × 5mg = 90.275mg/l Mg and 31945mg/l ÷ 1000 × 5mg = 159.725mg/l Cl)?
    Seems like there is way too much Chlorine then. I don’t think it works like this, and there might also be other parts besides pure MgCl² in the pulver. Or do you get your values because the Manufacturer writes onto the package how much g of Mg and Cl is in 100g of the pulver?
    Also I think different Magnesium and Calcium salts have different effects on pH and alkalinity, e.G. I think MgSO4 increases the alkalinity because of the Sulfates and MgCl² lowers the alkalinity and pH by having the acidic Cl²-Anion, while the alkaline Mg-Cation increases the pH.

    Also TWW uses Ca3(C6H5O7)2, which dissolves very slow in water, but if the water is boiling the dissolvement might be much better (As a reason by TWW by using it instead of CaCl², with having a better buffering propperties)

    Btw. I use TWW atm and the results aren’t that good as I want it. My coffee tastes too sour with it. (No matter if my TDS Is 1.25% or 1.45%)


    1. Calculating the individual atomic masses of Mg and the two atoms of Cl won’t be very precise. Instead look up the atomic mass of MgCl2 as a whole. This is because part of the mass of MgCl2 is stored as binding energy between the atoms. I calculate the amounts of Mg and Cl based on the atomic weight of Mg divided by atomic weight of MgCl2 times the mass of my MgCl2 minerals. If you have a hydrate form then you need to replace the atomic mass of MgCl2 with that of the appropriate hydrate (e.g. I have MgCl2 x 6 H2O).

      Different salts have different effects on pH, use aqion.onl to calculate it cause it gets complicated.

      I got some pretty good results with TWW but I heard with some very bright coffees it can be a bit overwhelming. Maybe try a recipe that isn’t as hard. Chlorine ions do not matter, chlorine taste and odor are caused by ClO, not just Cl ions.


  8. Hi Jonathan Gagné,

    I’m Duy Hieu form VietNam, can i ask you some question about technology about water? Because next month i will open my coffee shop but have some problem with water, i think you can recommend for me some brand really good water technology for espresso and hand drip.

    Thank you so much!!


    1. Dear Duy,

      Thanks for your comment. Working solutions for coffee shops are different than those for home because you will need much more water. Sadly, I don’t know what vendors exist in Vietnam, but I believe that solutions coffee shops typically adopt are based on reverse osmosis + re-mineralization filters. The first thing you should probably do is have your water tested by professionals so that you know its total alkalinity and total hardness. If it is already in a good range in the figures shown in this blog post, and tastes good, then you don’t need any filtering. Otherwise, the solution that works best for you will depend on where your tap water falls on the chart.

      I hope this helps a bit, and good luck with your coffee shop ! What’s the name, and in what city are you opening it ? I’ll definitely try it when I go back to Vietnam.


  9. This is a great article! Perhaps a trivial comment – similar to your bottle recipes, one can “cut” the Third Wave Water recipe to yield values similar to other waters on your graph. For example, using the calculations in your spreadsheet, a 60% cut of TWW-Espresso will produce an alkalinity of about 40 ppm and Hardness about 96 ppm and a 75% cut gives an alkalinity of about 51 ppm and Hardness about 120 ppm; That’s similar to Rao 2013 and Dan Eils waters respectively, although the mineral composition will of course be different from those two recipes.


    1. Thank you ! That’s a really nice trick. If you cut the TWW dose (instead of using more than 1 gallon of water), I recommend first diluting it in a small amount of water, stir it well and then cut this concentrate rather than cutting the dry minerals. This will avoid cutting in a way that changes the relative composition of the different dry minerals.


  10. Great article, I’m amazed at all the factors and variables that go into coffee water. It seems you mentioned the pro’s mostly use RO systems with minerals. Have you found any smaller scale for home use type of set up? I’ve searched and found this brand coffeewaterpro.com , they say they are up to SCA standard , is that even possible? Has anyone tested similar products before? I’m tempted to buy this but looking for alternative or similar products. Im also thinking of getting just the countertop purifier and trying TWW with it.


    1. Right now I make a concentrate out of dry minerals and put it in individual gallons of distilled water to craft Rao/Perger water. I used to buy the distilled water directly, but now I make it myself with a small ~200$ water distiller (takes a few hours to distil 1 gallon). Saves me some time but probably not money, as the gallons were cheap and boiling water requires lots of energy. I prefer this to TWW taste-wise.


    1. Hi Hans, do you mean spring water ? I’d recommend the Hanna Instruments freshwater total alkalinity photometer, it’s a small blue device that can tell you the total alkalinity in PPM as CACO3 without having to rely on imprecise color strips. They also sell a one for hardness (or Ca or Mg separately) but I couldn’t get my hand on those yet. Make sure you don’t get the saline water versions, they’re much easier to find and I don’t think they work for our purposes.


  11. Hanna Instrument Freshwater Checker:
    HI775 – Alkalinity
    HI720 – Calcium Hardness
    HI719 – Magnesium Hardness
    HI701 – Free Chlorine (unimportant?)

    Hanna Instrument Tester Checker Plus:
    HI98100 – pH

    That is a lot of equipment (ca. $70 each).

    Liked by 1 person

    1. You can find much cheaper pH meters that do a good job, and you can use just the alkalinity and Calcium ones, or even just the alkalinity one (this is the most important parameter). Your taste buds should work fine for chlorine.


  12. Resource: https://youtu.be/VAwxrxPFEMg?t=2177

    Red Sea Foundation Pro Multi Test Kit (R21510) (ca. $55)
    75 tests of each:
    Calcium Pro (Ca) – Accuracy: 5 ppm
    KH/Alkalinity Pro (KH) – Accuracy: 0.05 meq/l
    Magnesium Pro (Mg) – Accuracy: 20 ppm

    Would that be a possible cheap alternative?
    Plan: Go to spring water (check every 6 month?) use the test kit and a pH meter.
    Adjust the spring water with necessary substances (with math?).
    Or do I have to check the spring water more often and also during and after the preparation each time?


  13. Hi Jonathan, could you please share result numbers in mg/L of Rao / Perger recipe for:
    a) calcium (Ca2+), b) magnesium (Mg2+), c) HCO3-, d) TDS?


    1. Hey Jakub, sure ! Just look at columns R, S and V in the Google Sheet that is linked in the blogpost above.

      The URL for the sheet is: https://docs.google.com/spreadsheets/d/14tPm_1ndQl90GxdWJw_u7-7_Lzg0tPiVDaMzWC3u6bQ/edit#gid=0

      TDS is more complicated to estimate analytically. You can view an estimate in column Q, or an electric conductivity (most TDS-meters work by measuring this so you can put then in EC-mode) modeled by Aqio.onl in Column AN. I found that even this estimate isn’t too realistic, so I’ve written down some that I have measured in column AH.


  14. Thanks Hans, I had used the iOS version of this but not the website. It’s very useful as it contains the composition of many bottled waters, but I think they’re mostly European. Have a look at the bottled water spreadsheet I posted above, you can enter any bottled waters from the “mineral calculator” and then see what happens when you mix them together at different ratios.


  15. Thanks for the excellent post. It’s been an effort to put this information together before. This post has it all in one place.
    I caught one typo in the text above. “Your concentrate will be good for 50 gallons of water.” Gallons should be liters. 200g/(4g/L)=50L.
    It confused me a bit at first, then your spreadsheet link made sense. 4 grams for each liter of water. Thanks again!

    Liked by 1 person

      1. I just mixed the 1st batch. The brew water tested 297 (vs 272 calculated on your sheet) on conductivity & 140 TDS. Checks out. I was a bit concerned when the minerals didn’t seem to dissolve completely in the concentrate. I may run the mixture by a chemist to see their thoughts on solubility.
        The brew water tastes right. I’ve previously been using the 2 ingredient Barista Hustle recipe. We’ll see how this compares. Thanks again!

        Liked by 1 person

      2. Oh yes, I keep forgetting to add this mention but it is totally normal that the concentrate precipitates. It’s saturated in a few of the components; you just have to shake it well and make sure there’s no deposit at the bottom before using it. Once diluted more it won’t precipitate in your brew water.

        Liked by 1 person

      3. Thanks for the clarification. I’ll give it a shake and it’s good to go. The 1st brew was delicious, but that doesn’t really tell anything. I wanted it to be! haha


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