Water is the most essential element of life, because without water, you can’t make coffee.
The culture of drinking coffee has over the years grew to be recognised as a human necessity. It is no longer a luxury or an indulgence; it is a corollary of human energy and human efficiency. On the surface, coffee is an incredible simple beverage to make: just add have your ground up roasted coffee beans and add hot water and voilà there you go.

However, the science of achieving or getting the best coffee remains elusive. This has been a mystery to many coffee brewers, and many coffee aficionados have found it very hard on how to have a perfect balance of making the best coffee.

With a determination to have a flawless cup of coffee, coffee scientists have researched almost everything: that is the technique used to roast the coffee, the ratio of water to coffee to the methods of grinding the coffee. Today, we take a closer look at the ingredient that matters the most: water.

1. The Best Water Type for Coffee

Ask any coffee enthusiast if the type of water matters in their coffee and every one of them will (read: should) say yes. While many people have viewed water as an impure ingredient, water itself contains vast minerals that will influence the flavour of the coffee.

This has led researchers to pin down to one factor as a breakthrough to the science of having good coffee. And that is water quality.

espressoWater can transform the character of a coffee. It can accentuate its acidity, or wipe it out entirely. It can increase or decrease body, change extraction. It affects the way we roast and the way we brew. The ideal flavour of the drink is achieved with a modest mineral content in the water, and a high-quality coffee. But minerals will build up on the inner surfaces.

Water has a significant impact on the brewing cycle and ultimate taste of the final product. A certain amount of mineral in the water is necessary to produce a pleasant flavour and to aid the extraction of oils from the coffee bean. However, certain minerals make the water hard, which can be good and bad for the beverage. To ensure consistently great-tasting, premium water, filtration is the best solution.

Water is considered by many the most important ingredient in coffee because it makes up 98% of the drink, but it’s much more than that. It isn’t just an ‘ingredient’ that you add to roasted coffee seeds – water is the solvent that extracts the flavour compounds from the seed. It has a very active role. To dissolve flavour compounds in water, the water has to form chemical bonds with solids in the seed and carry them away.

2. The Chemistry of Water in Coffee – A Scientific Research

Water softeners remove metallic ions such as calcium, magnesium and barium. Through ion exchange, this process replaces the minerals in the water with sodium. Good coffee needs these metallic ions to bond with the flavour molecules in the coffee grounds.

Whereas water is rich in minerals such as calcium and magnesium, coffee has vast amounts of natural minerals and over 700 natural aroma compounds. It’s also worth noting that we have hard water which contains magnesium and soft water contains or is rich in sodium which most water softeners use to remove impurities. This is what led Christopher Hendon, a chemist from the University of Bath to focus on the way different kinds of water affect the extraction of chemicals more so the six chemicals that contribute to the flavour of coffee.

He analysed the relationship between water quality and specific parameters of roasted coffee to produce the highest quality beverage and to manage variations in coffee taste. And in his research, he found out that magnesium in hard water sticks to eugenol (a chemical found in coffee) and gives the results a very good taste. The study also found out that water softeners that are commonly used increase the sodium content in water. High magnesium ion levels were found to improve the process of extracting the coffee flavour from the beans though high bicarbonate levels were bad for flavour.

Calcium and Magnesium

Calcium and magnesium are metals dissolved as charged particles in water (Ca2+ and Mg2+). The positive charge is important because most of the flavour compounds in coffee are negatively charged when dissolved in water, which means they are attracted to the positively charged metal ions. If you’ve heard talk of ‘hard water’ by the way, it doesn’t mean whisky. It means water with a lot of calcium and magnesium in it.

Magnesium Ions, Calcium and Sodium to Help the Extraction

Magnesium ions in water aid the extraction of sharp, fruitier flavours, calcium emphasises heavier, creamy notes – and that ‘buffer’ is antagonistic towards sharper, acidic notes.

Magnesium will have the greatest effect on extraction, calcium slightly less and sodium still less again. While the magnitude of the effect of each ion is different, the balance of effect is roughly the same.

Magnesium-rich water is better at extracting coffee compounds and the resultant flavour only depends on the correct balance between both the ions in the water and the quantity of bicarbonate present.


Carbonate which is also another important component has the ability to soak up acid hence it helps to keep the acid level steady-it locks it up when there is too much of it around and it releases it again when there is a shortage. Carbonate also has a role in the health of your equipment. It’s a two-edged sword. A little bit of carbonate is useful because of that balancing trick where it binds up acid, but if there is enough calcium around, then heat encourages the formation of calcium carbonate.

When brewing coffee, the goal in mind is always to get to the heart of perfection. Most people seem to advocate for their own processes for achieving the best extraction, but the quality of water plays the largest role in the kind of coffee one will have at the end of brewing. Just as one would pair wine with certain or certain types of food, the same is true for the water and coffee you brew.

3. The Ratio of Coffee to Water

There is a ratio of coffee to water that is used and the best ratio to use is 17.4 units of water to 1 unit of coffee. This ratio will give you the best results since the solids will be dissolved in your coffee. Strong coffee has nothing to do with bitterness, caffeine, roast profile or content but has everything to do with the ratio of coffee to water.

4. The Best Water Temperature to Brew the Perfect Coffee

One has also to consider the temperature of the water that is used. In most cases, it’s good to maintain water temperature between 195 to 205 degrees Fahrenheit for optimal extraction. When cold water is used, it will result in flat and under-extracted coffee while water that is too hot will lead to the loss of the trademark taste of coffee.

The amount of time that the water is in contact with the coffee grounds is another factor that should be considered. Do not over-extract or under-extract. Brewing coffee is a kind of selective solvent extraction. There are delicious chemicals in the seed, and there are some truly nasty ones. The whole trick of brewing is for your solvent to collect the delicious ones and leave the others in the pack. We use temperature to change our solvent characteristics all the time in coffee.

Bottom Line

Brewing great coffee is as much a science as it is an art. Once you learn the principles that underlay the brewing process, you can develop a routine that suits you perfectly.

In conclusion, you can make good coffee taste bad but you can never make bad coffee taste good. And all this, of course, depends on how you’ve mastered the science behind the perfect cup of coffee.

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