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What is the Best Water to Use When Making Coffee?

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Besides the actual coffee that you select to brew with, water is the most important element that goes into a cup of coffee. The mineral content and ph level of the water you use, can have drastic effects on the finished product. Using the wrong water can ruin a beautiful coffee and nobody wants to see that happen.

At the most basic level, water chemistry isn’t a huge deal. Conventional coffee wisdom is, if your water tastes good for drinking, it will taste good for coffee. To a certain extent this is truth.

Here are a few basic coffee water brewing principles, if you think you have a water problem, start here.

If you want to cut to the chase and start with water that is made for optimal coffee brewing, pick up a box of Third Wave Water and see how much of a difference the right water can make to a cup of coffee. (I have used Third Wave Water for several years now.) For the DYIer there is also a recipe for making your own version of Third Wave Water via Tinker Coffee (.75 grams Epsom Salt and  .26 grams Baking Soda mixed in a gallon of distilled water).

Make sure you are using clean water that is free of off-flavors and odors. If you wouldn’t drink a glass of it, don’t make your coffee with it.

Filtering your tap water

If you are unhappy with the caliber of your at-home water, the first option that you have is to filter it. The SCAA water brewing guidelines state that water should be clean, odor-free, clear with no chlorine.

Pitcher filters like the Brita use activated carbon to remove some water impurities, odors as well as chlorine or chloramine if they are present. These types of filters are cheap and readily available, however, I have found them to have an annoyingly limited capacity, be cumbersome to use and in constant need of filter replacement.

There are also faucet mounted filters of this type. I have never used them, but they seem like they may be a more feasible option.

For many years, I used a Berkey water filtration system for all my household water consumption needs. Each filter lasts for up to 3,000 gallons and the system has a large capacity (mine held 3 gallons).

Soft or Hard Water?

While there seems to be some debate on the subject, I believe that using hard water makes a better cup of coffee than water softened with a home water softener.

Water hardness is a measure of the amount of magnesium and calcium that is dissolved in water. Water rich in these two minerals (magnesium in particular) are great at bringing out the best in coffee flavoring compounds. Replacing these minerals with sodium will produce a coffee that is flat by comparison.

Very hard water can destroy an espresso machine with scaling and thus it is a large concern in the pressurized coffee game. It has minimal impact on the equipment of a manual brewer. Regular kettle descaling and maintenance should make any scaling from hard water negligible.

One recommended resource that discusses water hardness, testing your water for hardness and water for coffee is Jim Schulman’s Insanely Long Water FAQ. This 17 page document is heavily espresso weighted but has some great general information as well.

According to Schulman, “It’s almost impossible to brew coffee with neutral pH water that’s too hard, since raising it to 95C will drop out the hardness in excess of 90 mg/l to 100 mg/l as scale”

If you have a water softener at home and are feeling incredulous, the easiest way to is to decide for yourself. Try it. Do a comparison test between your soft and hard water figure out which one you like better.

Using Reverse Osmosis Water

Reverse osmosis (RO) is a process where all the minerals are taken out of the water. What is left is water that has virtually nothing in it. You would think that this would be ideal for brewing coffee, but it is not.

Brewing with straight reverse osmosis water will produce a flat cup of coffee not unlike the coffee made with soft water.

Reverse osmosis water is missing all those magnesium and calcium minerals that enhance coffee flavor. There are, however, blending reverse osmosis systems that will mix back in mineral rich water. Some of these systems have the ability to customize the total dissolved solids level of your water.

A reverse osmosis water blend is a viable option for great brewing water. The SCAA recommends 150 mg/L total dissolved solids.

If you do not have a reverse osmosis system with blending capabilities, you can blend the water yourself. Try different ratios of RO water to tap water and see if it improves your coffee taste (20 – 25% tap water is a good place to start).

Bottled Water

If none of the above options are feasible or appealing to you, you can always brew your coffee with bottled water. Using bottled water is not a cut and dry issue either. Not all bottled waters are created equal. Bottle waters vary wildly in mineral content, pH and suitability for coffee.

“Bottled waters mostly come in two kinds, alkaline ones with massive mineral levels just below brackish, and acidic ones with mineral levels just above RO flatness. Very few have the intermediate hardness levels found in most municipal waters” (Schulman, 11).

Your best options for bottled water are going to be labeled drinking or spring water. Schulman recommends Crystal Geyser or Volvic. If you are buying bulk five gallon water blended RO jugs, try to locate a source that is using magnesium for adding hardness back into the water instead of calcium (this may be rather difficult).

It’s Going to Be Okay

Don’t freak out. It’s going to be okay. The good news is that most basic water issues are quick fixes and easy work arounds.

While good water is a crucial component of getting the most out of a coffee, adding awareness to the water we use can add extra mental exertion, hassle and expense to brewing coffee manually at home.

If you like the coffee you are brewing at home, there is no need to mess with your water unless you are curious. If you can’t figure out why your coffee is not up to cafe standards, water might be something worth investigating.

Here are a few small things you can do to investigate if your issue is water related:

  1. Have a brewing party- Have some friends over and brew some coffee. Have each friend bring a different water either from their house or from the store. You can even get crazy and try some waters like distilled for educational purposes.
  2. Do some cuppings- If you don’t have a lot of people around you that are coffee fanatics, you can get a few different waters and do a cupping on your own. Try three or four different waters side by side with the same coffee.
  3. Try Third Wave Water- Third Wave Water has been designed as a mineral additive that can be added to distilled water for a optimized brewing water.  You can also make your own optimized brewing water if you are feeling ambitious (it is actually pretty simple). Tinker Coffee recommends mixing .75 grams of Epson salt and .26 grams of Baking Soda in a gallon of distilled or reverse osmosis pure water.
  4. Ask your barista- Is there is a particular coffee shop that brews coffee you admire? If you can’t seem to replicate the experience at home, ask the coffee shop if you can have some water. This may seem like a strange request but explaining to a barista that you are trying to diagnose your at-home brewing should clear up any issues. Most baristas would love to give you a sample I’m sure.

This really just scratches the surface of water chemistry. For further reading you can check out the links below. Something that is also very interesting and will hopefully be the topic of a future post is Maxwell Colonna-Dashwood’s Symposium talk about water chemistry and mineral content. I found this fascinating and have some definite ideas and thoughts on the matter.

What if your issue is not water related at all? Check out Troubleshooting and Fixing a Bad Cup of Coffee for my tips on coffee fixes

What about you? Do you have thoughts on brewing water or methods for making sure your water isn’t holding back your coffee’s true potential? Let me know below.

Sources:

Jim Schulman’s Insanely Long Water FAQ

The pros and cons of water treatment for a perfect cup of coffee

SCAA water standards

Tinker Coffee Water Recipe

(Originally Published June 16, 2015- Updated September 10, 2020)

14 Comments

  1. joe rico

    Hello, I have a question of water choice for my coffee.
    I use a French press for my daily cups of coffee; usually two cups (6-7oz ea).
    My coffee brands vary- Starbucks, Peet’s, Coffee Bean ( 2 tbl ea cup).
    I also vary/experiment with my water: tap, RO, bottled.
    I heat the water in a kettle and await the steam whistle. Now, since I only make two servings does it really which water source I use? The difference is barely noticeable; sometimes I try to convince myself that RO makes a better cup than tap. But really, it’s only for two cups. Should I expect a difference? My tap water is has a good rating… your article suggested a blind taste test. Just wonderin’. Thanks

    • John

      Hey Joe!

      Thanks for taking the time to leave a comment. There are a few things going on here that I would like to address:

      1. Batch size- It doesn’t really matter if you are making 2 cups of coffee or 12 cups of coffee, the water that you use will still have a huge impact on how the coffee extracts and tastes.

      2. If it ain’t broke don’t fix it- While I encourage experimentation and trying to change variables to improve your coffee, if you enjoy your coffee how it is, there is no reason to change it. Don’t worry too much about what water you are using if you like how your coffee tastes.

      3. About blind taste testing- For curiosities sake, you could do a blind taste testing. If you really want to see which one you prefer, do a blind taste testing. If you want to see if there is really much difference between two waters, do a triangle taste test. A triangle test is a blind taste test where there are three cup of coffee and two are the same. Your job is to pick out the one that is different.

      I hope this helps,

      John

    • Scott Barton

      If you want the smoothest, richest flavored coffee you have ever had it starts and ends with the water you use. I actually found this out by accident after ordering an all natural water ionizer called pure hydration. This device filters out the impurities from the water, raises the pH and has the ideal amount of magnesium, calcium and sodium to brew an amazing cup of coffee. Like I said it was by accident that I noticed this, I bought the device on Amazon because of the health aspects of the water but have since ordered the replacement cartridges from the manufactures website cosanusa.net. Try and let me know what you think. Scott

  2. RAH

    Link address incorrect: http://www.watertechonline.com/articles/168503-the-pros-and-cons-of-water-treatment-for-a-perfect-cup-of-coffee

    Current link is: http://www.watertechonline.com/the-pros-and-cons-of-water-treatment-for-a-perfect-cup-of-coffee/

    Your article was very helpful. I am planning on using RO and an inline supliment for making softeened and pH correct water. A work in process.

    RAH

    • John

      Thanks RAH! I will get those links fixed. Happy Brewing.

  3. Kaffeemaschine

    Thanks for this post. Very useful!

  4. Stella Brown

    Hey John,it’s such an informative article you had shared.thanks for sharing this.it will help me to make coffee far better. Keep posting this type of post. Good wishes.. :)

  5. Gabriela

    Hello,
    Im trying to meassure the salts according to your instructions.
    .75 and .26 grams are less than 1 gram an a bit difficult to do with my home scale. Is it possible that is 75 and 26 grams which will be close to 5 and 1 2/3 of a teaspoon?
    Thank you.

    • john rosati

      The person that wrote the “recipe” to obtain “good water” escaped from a sanitarium. :
      LOL.

      Can you imagine do the “biological” concoction all the time? I have a central water softener plus an osmosis system at the sink because where I live the municipal supply water is heavy in minerals. I have tried to mix half and half with good results., Coffee needs some minerals. I use a semi professional espresso machine and a good grinder which basically is the secret, A professional grinder. Unfortunately they are expensive, aroud $600. T

  6. Dave

    I’ve just moved to Madison, WI, and our current and future permanent one has/will have a water softener. I lived in Topeka, KS, which has hard water. I manually brew, pour over. I’ve noticed a difference immediately: the water takes forever to seep through the grounds and filter. I have a burr grinder, medium grind. It doesn’t take long for the water to slow to literally drops at a time. My cone filter has 3 holes.

  7. Russell Volz

    John,

    I’ve been wondering about this subject myself, so I enjoyed your article. I think your best advice was, “If you like the taste of your water, then it’ll be fine for your coffee.” Another favorite was, “Not all bottled water is created equal”. That’s for sure! I’ve had tossed out bottled water because it tasted so sterile.

    One new thought for you. If someone is drinking burnt and bitter industrial coffee, I think the quality of the water is their last concern. They’ll never notice the quality of the water. On the other hand if they’re drinking good quality smooth coffee, then the water becomes more important.

    My suggest for finding good quality smooth coffee is to just search the internet for “smooth coffee”, or “smoothest coffee”, or “smooth coffee beans.”

  8. Nasir

    Great info about the coffee making. Thank you for sharing this article. Such quality content always helps the people getting valuable knowledge. I would like to mention that I have shared useful reviews of different coffee machines in the mentioned site.

  9. alison

    Have you thought about adding food grade Calcium Carbonate instead of the Sodium Bicarbonate? That would replace the Sodium ion with the Calcium ion.

  10. Caleb M

    I recently tried brewing a Kenyan coffee with purified drinking water with minerals added, and my tap water filtered with a PUR water filter. To my surprise the filtered tap water tasted a great deal better then the purified drinking water with minerals added.

    The purified drinking water tasted under extracted and sour compared to the filtered tap water.

    Minerals that were in the purified drinking water are the following: calcium chloride, potassium bicarbonate, and magnesium chloride.

    Would these minerals be optimal for extraction?

    Thanks!

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