Best Water For Coffee: Beginner’s Guide


Are you having a hard time tasting the flavor notes, listed on the bag of your specialty coffee beans; or you’re simply trying to make a great cup of Joe, but something always seems a bit off?

If the answer is yes, then you may be neglecting the importance of using the best-suited water for your homemade coffee.

No matter if you use an espresso machine, a drip coffee maker, a French press, or a pour-over dripper, you should know that you can’t get excellent results if you don’t take into consideration your water’s parameters.

And I’m not only referring to temperature, but also pH, and hardness. Even if you have a single-serve maker, such as a Keurig, there will be a significant difference in the flavor between a cup made with tap, bottled, distilled, spring, or, say, reverse osmosis water.

But which one of the aforementioned water types is the best for your coffee maker and why?

Is soft water always better than hard?

Are there any water brands that offer the best product exclusively targeted for coffee enthusiasts?

In this beginner-friendly guide, I’ll give you the basic knowledge that will provide you with a better understanding of how water influences your coffee’s flavor and the longevity of your home machine.

So let’s dive in!

What’s the Best Water for Coffee: Quick Overview

It’s generally considered that the best water for coffee is the one that meets the standards, established by the Specialty Coffee Association (SCA). [1] It should have moderate hardness and alkalinity and neutral pH.

You can find these standards in the following table:

Characteristic: Target: Acceptable Range:
Odor Odorless
Chlorine 0
Hardness 50 to 175 ppm CaCO3 50 to 175 ppm CaCO3
Alkalinity 40 ppm 40 to 70 ppm
pH 7 6 to 8
Total Dissolved Solids (TDS) 150 ppm 75 ppm to 250 ppm

The water characteristics above are favorable for coffee brewing, not only because they improve your cup’s flavor.

Making sure you add coffee-suitable water to your coffee maker or espresso machine will prevent malfunction and increase its lifespan.

With that being said, when it comes to flavor, the ideal water parameters for coffee making are different for different types of coffee beans and roasts.

Therefore it’s safe to say that the best water for coffee is the water that the coffee beans were roasted to (i.e. the water that was used during taste testing when the roaster was figuring out the roast profile).

In other words, if you want to sense the flavor notes, written on the bag of your specialty coffee beans, ask your roaster what water parameters you should aim for.

You can also ask the roaster or your local cafè to give (or sell) you a bottle of the water they use.

Water Chemistry and its Influence on Coffee Extraction

For you to clearly understand how water influences coffee, we shouldn’t simply look at it as an ingredient, but as a solvent that plays a vital role in the process of coffee extraction.

Therefore I need to shed some light on some of the essential properties that are used to characterize the chemistry of water.

These are pH, general hardness (GH), buffering capacity (alkalinity, KH), and total dissolved solids (TDS).

If you were bad at chemistry in school, don’t worry.

I’ll try to explain everything in layman’s terms, so you’ll be able to easily achieve a grasp of the influence of water on coffee making.

pH

The pH value refers to water being either a base, an acid, or neither (neutral).

The range goes from 0 to 14. A pH of 7 is considered neutral, a pH above 7 – basic or alkaline, and a pH below 7 – acidic.

The ideal water pH for coffee is neutral, with a value of 7. Nevertheless, the acceptable pH range for coffee brewing, according to the Specialty Coffee Association (SCA) is between 6 and 8. [1]

If your water doesn’t fit within this range, you may be disappointed with how your coffee turns out.

For example, if you prepare a cup with water that’s too alkaline (pH above 8), your coffee will likely turn out flat.

With that being said, if we are to discuss the pH in the context of coffee extraction, we definitely need to take into consideration the water’s alkalinity, i.e. buffering capacity.

Important: Don’t confuse the term “alkaline” and the term “alkalinity”. The latter refers to buffering capacity, while the former – to a solution with a pH above 7 (i.e. base).

Buffering Capacity (Alkalinity)

The buffering capacity represents the ability of water to maintain a stable pH when acids or bases are added to it.

Generally, water’s buffering capacity is due to its bicarbonates and carbonates.

The terms “carbonate hardness” (KH), “buffering capacity”, and “alkalinity” are pretty much used synonymously.

Author’s Note: Technically, carbonate hardness (KH) measures something different than alkalinity.

When you boil water, its bicarbonates (mainly HCO3) react with magnesium (Mg 2+) and calcium (Ca2+) and form a solid, that we all know as limescale.

The carbonate hardness (KH) shows the maximum amount of magnesium (Mg 2+) and calcium (Ca2+) that can be paired with the bicarbonates and form limescale.

More often than not, the carbonate hardness of water equals its alkalinity, as the bicarbonate ions are usually less than the calcium (Ca2+) and magnesium (Mg 2+) ions.

Nevertheless, if it’s the other way around, and the bicarbonates prevail, the KH will be higher than the general hardness (GH) – a parameter which I am to discuss in a bit.

If the KH is higher than the GH, then the KH value will actually represent the water alkalinity, while the GH – both the general hardness and the carbonate hardness (KH).

While the pH shows the current state of the water, it doesn’t give you any information about how easy it is to change its acidity, which is crucial when discussing coffee extraction.

If we add acid to water with high alkalinity, its high buffering capacity will absorb and neutralize the added acid and the pH will remain stable.

Coffee tends to be acidic. Since alkalinity buffers out its acidity during extraction, it makes your cup of Joe taste less sour.

If the water that you use for coffee making has too low alkalinity, the acids in coffee will get too intense and ruin the flavor of your brew.

Therefore you’d want your water to have a sufficient buffering capacity.

On the other hand, if the water’s alkalinity is too high, your coffee will lack complexity and crispness and will turn out dull.

Furthermore, water with too low alkalinity may lead to corrosion of the internal metal parts of your coffee maker or espresso machine.

According to the Specialty Coffee Association (SCA), the ideal alkalinity for coffee should be at or near 40 ppm. The recommended alkalinity range is between 40 ppm and 70 ppm. [1]

To measure the buffering capacity of the water you use for coffee making, you can use this API test kit.

With it, you can measure the carbonate hardness (KH) and the general hardness (GH).


Click here to check out its price on Amazon.

General Hardness

The general hardness (GH), also known as total hardness, refers to the total amount of magnesium (Mg2+) and calcium (Ca2+) ions in the water.

Other ions such as aluminium, manganese, and iron also contribute to the general hardness, but they make an insignificant fraction of it, as their amount in drinking water is usually very low.

General hardness is measured in parts per million (ppm) or milligrams per liter (mg/l).

Water with GH of:

  • 0 to 70 ppm is considered very soft;
  • GH of 70 to 140 ppm: soft;
  • 140 to 210 ppm: medium-hard;
  • 210 to 320 ppm: fairly hard;
  • 320 to 530 ppm: hard. [2]

Calcium (Ca2+) and magnesium (Mg2+) help water extract flavor from the coffee. [3]

Therefore you can’t make a great cup of Joe if your water is too soft.

On the other hand, using water that’s too hard will have an adverse effect on the extraction of flavor compounds.

If the total hardness is too high, you’ll end up with coffee that lacks nuance and sweetness.

Furthermore, using water that’s too hard will cause a rapid accumulation of limescale, which may damage your espresso or filter coffee machine.

To prevent a malfunction, you will need to descale your coffee maker too often, which can be quite frustrating.

According to the standards of SCA, for coffee making, you should use water with a total hardness of 50 to 175 ppm. [1]

Most test kits measure the general hardness in units of CaCO3, but this doesn’t mean that the hardness actually comes from calcium exclusively. It shows that the hardness is equivalent to that much CaCO3 in water, but may also include magnesium.

What’s also worth noting is that magnesium and calcium affect coffee extraction differently.

There is some evidence that magnesium extracts more desirable coffee flavors compared to calcium. [3]

Making coffee with water that’s high in magnesium may result in higher caffeine content and more intense flavor than coffee, brewed with water that’s high in calcium.

Furthermore, it’s considered that magnesium forms scales that are slightly more soluble compared to calcium scales.

Therefore it may be better for your coffee maker and espresso machine to use water high in magnesium, not calcium. This may reduce the negative impact of limescale on your device.

Total Dissolved Solids (TDS)

The total dissolved solids (TDS) measurement refers to the total concentration of all minerals, inorganic, and organic substances, dissolved in the water.

It’s measured in parts per million (ppm) or milligrams per liter (mg/l).

It’s generally considered that water with TDS that’s too low will over-extract coffee, while water with a high TDS will result in under-extraction.

That’s why the SCA has come up with a target TDS of 150 ppm. [4] The acceptable TDS range of water for coffee is between 75 and 250 ppm.

With that being said, TDS doesn’t give you much insight into the composition of the water you use.

Even if your tap water has a TDS of 150, this doesn’t mean that it’s ideal for the extraction of your coffee.

You don’t know what stays behind the TDS value – it may be magnesium and calcium that contribute to this number, but it may also be iron or, say, copper.

Knowing what’s the GH and KH of the water you use for coffee making is much more valuable than knowing its TDS.

Nevertheless, it’s more convenient to use a TDS meter than to rigorously measure the alkalinity-to-hardness ratio of your water.

Click here to check out the price of this TDS meter by DUMSAMKER on Amazon.

Using this type of device is definitely helpful.

It can give you a better idea of whether your tap water is suitable for coffee, or how your filter pitcher affects the TDS of tap water.

Nevertheless, without knowing what the dissolved solids in our water actually are, we can’t tell whether we’re using the best water for our coffee beans.

So if you’re aiming for excellent results, I’d recommend using a GH and KH test kit.

Different Types of Water and Which One Will Work Best For Coffee?

Now that you know a bit more about water chemistry, let’s have a look at the basic characteristics of the different types of water.

This will give you more clarity and improve your judgment when it comes to which one to use for coffee making.

So let’s define the different types of water and their compatibility with coffee.

Tap Water

Photo by Kaboompics .com from Pexels

Tap water can be acceptable to use for coffee making, as long as it tastes good, but could it be your top pick?

The basic rule that all beginner coffee enthusiasts follow is to make coffee with water that tastes good on its own.

Sometimes the water that comes out of your tap tastes like chlorine, which should be avoided.

According to the SCA, the best water for brewing coffee should be odorless and free of chlorine.

Chlorine kills parasites, bacteria, and viruses and is actually added by governmental agencies that are responsible for the treatment of tap water.

As we already know, hardness and alkalinity are also essential when discussing coffee extraction.

So another disadvantage to using tap water for coffee is that you don’t really know what its mineral content is.

Even if it’s odorless and tastes good, it might not be ideal for coffee brewing, as its hardness or alkalinity may be too high or low.

To get a better understanding of whether your tap water is suitable to use for coffee, you can check out the website of the local water authorities where its chemical analysis is usually published.

The other option is to use a KH and GH test kit, or at least a TDS meter.

Unfortunately, more often than not, tap water is too hard, and using it in your coffee maker or espresso machine may cause the rapid accumulation of mineral buildup.

Filtered Water

Filtered water is typically run through carbon filters that remove chlorine.

Using filter pitchers such as a Brita will remove the undesired impurities and odors of your tap water.

This water filtration method is the easiest and the most cost-efficient if you’re trying to make improvements in your coffee brewing.

When it comes to water hardness, Brita filters reduce it, but only a bit.

So if your tap water is too hard, running it through a filter pitcher may not reduce its hardness sufficiently.

I’ve done some testing and I’ve found that a Brita actually brings down hardness quite a bit, but only when it’s brand new.

As the filter wears out, the softening properties of the pitcher decline.

Furthermore, Brita filters don’t really affect alkalinity.

Jim Schulman gets reports similar results in his “Insanely Long Water FAQ” (click here to check it out).

Nevertheless, it’s still better for your coffee maker to filter your tap water, before pouring it into the water reservoir.

I also found out that there are magnesium mineralizing filter pitchers such as this one by BWT (Amazon link).

Along with its activated carbon, it also has an ion exchanger that swaps limescale and heavy metals for magnesium.

Since some sources suggest that magnesium improves extraction and has a positive impact on coffee flavor, it seems like this jug may suit the purposes of coffee making better.

Still, I haven’t tried it out, so let me know if you have, in the comment section.

Distilled water

The process of water distillation involves boiling water, turning it into steam, and condensing it back into liquid into a separate container.

The impurities and the minerals in the water that have a higher boiling point are left behind.

Distilled water’s KH and GH are as low as they can get (~0).

As discussed in the water chemistry segment of this post, such water parameters will harm the extraction of coffee flavors and may lead to corrosion of the internal parts of the coffee machine.

Therefore using distilled water for coffee making isn’t a good idea.

Furthermore, many home coffee makers, such as Keurig, detect the mineral content in water through their sensors.

So if you add distilled water into your coffee maker’s water reservoir, it may not realize that it’s full, and you will receive an error message that states “No water”. So you want be able to make a cup.

If you’re interested, you can check out my post on why distilled water isn’t good for coffee where I dive into a bit more detail.

Reverse Osmosis (RO) Water

Reverse osmosis is a process of water purification, which involves pressing water against a fine semi-permeable membrane whose intended purpose is to only let water molecules pass through it.

This method removes 90 to 99% of the impurities and minerals from the water.

Therefore the water parameters of RO water are pretty similar to those of distilled water.

The RO purification is less expensive than distillation and it’s more widely spread.

Since reverse osmosis strips out the mineral content, the nearly pure RO water, isn’t ideal for making coffee.

Its alkalinity and hardness values are below the acceptable range for coffee.

Therefore, if you use pure RO water when you prepare your cup of Joe, it will likely turn out bad.

Furthermore, the low buffering capacity of RO water may result in water that’s too acidic, which may lead to corrosion.

With that being said, many coffee shops have reverse-osmosis systems that also remineralize the water, by adding the right amount of magnesium and calcium back in.

Ion exchange water

Through the use of ion exchange water softeners, the water passes through a polystyrene resin which usually attracts calcium and releases a sodium ion in its place.

This reduces the calcium hardness but doesn’t affect water’s alkalinity.

Don’t worry – the sodium ion won’t make your coffee taste salty.

Furthermore, this ion exchange will reduce the formation of limescale.

There are also ion-exchange resins that replace bicarbonates with hydroxide, chloride, or sulfate ions, which reduces alkalinity, without affecting water’s hardness or heavy metal content.

Dual ion exchange water systems do exist as well.

They affect both hardness and alkalinity.

Ion exchangers are usually less expensive than RO systems, but they need to be recharged often. This is so, because when water passes through the resin, it releases its sodium and/or hydroxide ions, and from one point onward, there won’t be anything left to soften the water.

Bottled Water

The GH, KH, and TDS values of different brands of bottled water vary within a wide range.

You can look for a list of the mineral content of a particular brand of water on its bottle (usually described as TDS).

If you’re lucky enough, you’ll be able to get more insight into whether your spring or mineral water of choice is suitable for coffee brewing.

Unfortunately, many bottled water options have GH and buffering capacity that is either too high or too low, so they can’t be considered optimal for making coffee.

You can learn more about different types of bottled water by visiting this article.

Another disadvantage of using bottled water for coffee brewing, be it spring or mineral, is that it can get quite expensive. Furthermore, it’s not the most eco-friendly option out there.

There are a few brands of water that have a good reputation within the coffee community. Here are two of them:

Crafting Custom Water for Coffee Brewing at Home

There are other ways to get the best water for your coffee’s flavor that won’t harm your espresso machine or drip coffee maker.

  • By adding a proper amount of minerals to distilled or RO water you can get the optimal KH to GH ratio for coffee brewing.

    • You can do that through the use of mineral packets, such as those by Third Wave Water to make the best water for your homemade coffee/espresso. It’s quite easy to use these small mineral sticks – just dissolve one of them into a gallon of water, shake, and the water will be ready for use.
    • You can also increase the alkalinity and the hardness of distilled or RO water, and bring it within the desired range, by simply adding Epsom salt (for magnesium) and baking soda (for buffering capacity/alkalinity). You can check out this recipe by Barista Hustle if you’re interested in trying that out.
  • Another way of crafting your own water for coffee at home is to mix tap water and RO/distilled water.

    It’s preferable to use charcoal-filtered tap water (run it through a filter pitcher, such as the Brita), especially if it has an unpleasant chlorine odor.

    The addition of tap water to the RO or distilled water will raise its hardness and alkalinity.

    The thing is that you need to measure your tap water’s parameters to decide what will be the tap-to-distilled water ratio that you’re going to use.
  • If you’re lucky and you live in an area where the water that comes out of your tap is soft enough (but not too soft), just use a charcoal filter (such as a Brita pitcher) to improve its taste and remove undesired odors.
Reminder: Ask your roaster for the parameters of the water the coffee beans that you buy were roasted to (or simply ask if it’s possible to buy a bottle of this water).

As stated in this article on The Role of Dissolved Cations in Coffee Extraction by Department of Chemistry, University of Bath, Claverton Down:

“It should be noted that there is not one particular composition of water that produces consistently flavorsome extractions from all roasted coffee.”

“Furthermore, each bean is roasted to taste optimal when brewed with the water it was roasted to.”

Christopher H. Hendon, Lesley Colonna-Dashwood, and Maxwell Colonna-Dashwood

Final Words

I hope that you found my guide useful and know you know what you should look for when trying to get (or make) the best water for an excellent cup of coffee.

Feel free to share your thoughts in the comment section below

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