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In this article, I will go over why you should not be using regular tap water for your coffee, and what options you have, the best way to determine how hard your water is.

And answer questions like how to find good coffee water? And why can’t tap water be used? 

Why is Water Important?

A good cup of coffee is simple. It consists of two ingredients: coffee beans and water.

The former lacks attention. There is plenty of useful knowledge about coffee beans, how to grow, roast, grind, brew, and so on. 

But what about the water? Coffee water rarely becomes a slit in mainstream media.

But the fact is that water is at least the second most important ingredient in a cup of coffee – and maybe we should actually give water a shared first place.

After all, it would be completely impossible to brew coffee without water.

Short and Straight

The direct answer to which type of water should be used in your coffee would be:

  • Special coffee must be brewed with soft water to obtain a sweet, aromatic and nuanced cup. 
  • You can use bottled water.
  • You can also ‘mix’ your own coffee water, but I do not recommend it unless you are both a big coffee or chemistry nerd. It is simply incredibly complex. You will almost certainly spend many hours in a state of deep frustration. 

Why can’t You Use Tap Water?

If you are like the 99 percent of us, you brew coffee with water from your tap. 

You may be thinking right now that it tastes just fine, but believe me, once you have compared coffee brewed with proper water, you have no doubt.

I experienced that even after living abroad, where I had only brewed coffee with good bottled water.

Suddenly, the same coffee was far less aromatic when I tried brewing with tap water in Bangkok. It was, to put it mildly, a sad experience, compared with good water.

“Good beans brewed with bad water can be compared to listening to music on a couple of miserable speakers: Yes, you may recognize the contours of the delicious guitar and innovative synth, but to really get the full benefit you should have a pair of speakers that can play clean. That is, reproduce bass, midrange and treble clearly.”

To stay in the music metaphor, a serious shaker can actually be compared to a music producer. That person will have found a shake profile that fits the bean by ‘cupping’ it to a specific type of water. 

Most people will probably think that it is weird to use specific water for their coffee in the general population. But people working in the industry agree that water has a huge impact on brewed coffee quality.

Water is a Key Ingredient in All Beverages

In fact, it is the same when it comes to beer brewing. 

That is the very reason why you have different beer traditions in many countries.

One place is suitable for pilsner, while you can make ale and stout in other areas of the world. 

If you want to experiment with brewing beer at home, with a state guarantee you will have to familiarize yourself with water chemistry. 

If you are a coffee roaster who spends money on freshly roasted beans and quality equipment, then it also makes good sense to give water a thought or two.

PRO TIP: “Water and roasting also go hand in hand. A lightly roasted coffee requires very soft water to shine. Dark roasted coffee is easier to brew with hard tap water.”

tds meter amz

A TDS meter is an easy and inexpensive way to control your water. You can get yours here, on Amazon.

Optimal Water for Coffee

But what is the best coffee water? Suddenly it is harder to come up with a clear answer.

The thing is that once you start studying coffee water, you move into a deep, deep hole of esoteric nerdy.

You can compare it to studying philosophy: when you start to question the most important things in life, you suddenly find yourself on rocking ground. Everything is in limbo, and nothing is safe.

In the end, it comes down to availability, and how far you are willing to go to get that optimal coffee experience.

I recommend you use bottled water for normal people, and I also recommend you get a water hardness meter, linked above, to test your water, as that (surprisingly) has a big impact on the taste of your coffee.

Lime and Magnesium are Coffee’s Best Friends

We need to go to England to find some of the great pioneers in coffee water. 

Maxwell Colonna-Dashwood, a three-time winner of the British Barista Championship, was frustrated that his coffee was of varying quality depending on the water. 

Together with chemist Christopher H. Hendon, he investigated what was needed to create the best coffee water. It culminated in a scientific report and a popular scientific book called ‘Water for Coffee’. 

During their experiments, they found that it was actually only three components that play an essential role in extraction: magnesium, lime, and bicarbonate.

Magnesium and lime pull the flavors out of the coffee, while bicarbonate is a buffer that ensures that the pH does not fluctuate too much. 

water for coffee book

In the past, much has been said about the unit of measure TDS (total dissolved solids) when the discussion has been about coffee and water. But in fact, Colonna-Dashwood’s study proved less important. 

Instead, it is about the very relationship between lime/magnesium and carbonate hardness. The hardness should be between 50 and 175 ppm, and the carbonate hardness should be between 40 and 75.

Generally, there should be about a 1:2 ratio between the buffer and the total hardness. If the magnesium content is too high relative to the buffer, then the coffee will be over-extracted and taste out of balance. On the other hand, if the relationship is reversed, the taste will be flat, sharp, and empty. 

How to find water with the right ratio? In nature, it doesn’t actually occur, so Colonna-Dashwood’s solution is to make it yourself.  

Using either distilled or reverse osmosis water, carefully measured minerals can be added and thus hit the perfect composition. At least in theory. 

The Danger of Playing an Amateur Chemist

In practice, it is another matter to construct your own brewing water. I’ve talked to quite a few coffee roasts, who have a hard time getting a good result with homemade water.

The task is further complicated because it is virtually impossible to find water without minerals in normal supermarkets.

Yes, you can find distilled water at the pharmacy for USD4 for 1 liter. You can also buy semi-expensive appliances for making osmosis water.

Abroad, it is much easier to find osmosis water, as tap water is often of poor quality. 

However, I would recommend using one of the other solutions unless you are a hardcore coffee nerd who is ready to spend a few hours experimenting (and potentially drinking many cups of gruesome chemically tasting coffee). 

Third Wave Water is an interesting option where a mineral blend is made for you, but again it requires you to have ultra-pure water you can add it to. 

PRO TIP: It’s important to remember that one thing is a theory; another is practice. While it may be specious to dream of perfectly tuned water a la Colonna-Dashwood, you have already reached 95% of the way with bottled water like Nornir.

Also, remember that it is essential to be consistent with your water. Perhaps more important than obtaining the perfect composition.

That way, you can change and optimize other elements of your brewing such as grinder degree, shaking profile, and water temperature.

The Filtering Jug can be Your Ally

brita filtering water

If you are interested in a Brita water filter jug, you can find them at great prices on Amazon.

Do you think it’s a strange thing to buy expensive bottled water to make a proper cup of coffee? 

Then it’s because you haven’t tasted the difference yet. Try it before you judge it!

However, the spring water solution has a couple of challenges. It is expensive and a bit cumbersome all the time to buy a lot of water homes in the long run. 

If you live in a part of the country where the water is relatively soft by international standards, it may be a good solution to use a pitcher to filter water.

There are several different models on the market, for example, Brita. 

A filtration jug is cheaper than mineral water and lighter in length. 

However, it should be noted that the filtering mechanism in these jugs must be changed every month. 


I will ask you three questions: do you buy good beans? Do you have an expensive grinder? And, do you brew carefully? 

If you can answer yes to all three things, then water is just the last factor that can take your coffee from good to divine.

There are many theories about water, and the coffee world still has a lot to learn about the subject. 

However, the most important thing to do for the common coffee lover is to stop using water directly from the tap. Whether to buy bottled water, use a filter pot or mix your own from scratch depends on where in the country you live and how much resources you are ready to invest. 

Although TDS is not the most accurate way to measure water, it is the easiest and cheapest solution.

In addition to being miserable for coffee, most tab water is also harmful to electric kettles and bathrooms due to a large amount of lime. The country’s water utilities have actually begun to consider softening the water to help the community save huge amounts of maintenance. But until that happens, we coffee lovers must do the hard work themselves. 

Best Water For Coffee.

Lastly, you can check out another one of our articles about why the right water is important for your coffee.

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