The Importance of Water in Coffee Making

It’s pretty obvious that a cup of coffee is largely made up of water. 98%, in fact. Which means that the quality of water plays a significant role in the taste of coffee.

For those who want to get the best cup, here are a few basic coffee water brewing principles and tips.

pH Level

pH is an indicator of acidity and alkalinity. A pH level of less than 7 indicates an acidic solution whereas a level of more than 8 indicates an alkaline solution.

For coffee brewing, a higher pH level means greater extraction of flavours – but that doesn’t mean you should be using water that is on either spectrum of the pH range. According to the Specialty Coffee Association (SCAA), the recommended pH is between 6.5 and 7.5 to ensure that your cup of coffee is well-balanced.

Soft or Hard Water

a man standing on a water puddle with a cup of coffee in his hand
As raindrops touch the ground, it picks up minerals, turning it from soft to hard water. Photo from Ian Keefe.

In the water world, not all water is equal. Depending on its mineral content, it is considered hard or soft.

As rainwater falls, it is naturally soft. But as it makes its ways through the ground, waterways, and pipes, it picks up minerals such as chalk, lime, magnesium and calcium, making it hard water. But fret not, these minerals are considered essential to our health, which makes it the preferred drinking water than raindrops.

Flavour extraction from coffee grounds requires small amounts of these minerals. That is why the ideal hardness is 75-250 mg/L, with a target of 150mg/L.

What type of water is hard or soft enough for coffee? Find out in the next section.

Type of Water

Refilling a water bottle from a water tap
Run through tap water through a water filtering system or jug before using it to brew coffee. Photo from LuAnn Hunt.

Bottled spring water is between 220-480ppm whereas distilled water is only 0.5ppm or less. That is why when it comes to making coffee, leave out distilled water as it is overly purified.

“Can I use tap water?” The answer is yes, if your country’s tap water has been 100% approved as safe to drink. For example, in Singapore, where tap water is known to be ready for consumption, it has approximately 80 ppm which makes it a good start for coffee brewing. 

Nonetheless, there is a chance that tap water contains traces of compounds that impart a slightly acidic or metallic taste to your coffee. To prevent that, we recommend running your tap water through a water filtering system or a filter pitcher. Don’t forget to change the filters regularly, just like how you have to descale your coffee machine once every three to four months.


a kettle placed on a table with a plate of bagel on the side
Temperature control is just one reason to spend a little more on a quality electric kettle. Photo from De’Longhi.

The temperature of water strongly influences the rate that flavours are extracted from coffee grounds. The ideal temperature for water is slightly below the boiling point at 90-96 degrees.

If the water is too cold, you will get an under-extracted brew. Too hot and over-extraction will occur, resulting in a bitter-tasting brew.

The most accurate way to test the water temperature is to use a kitchen thermometer. But if you don’t have one, ensure you invest in a quality electric kettle that boils water perfectly to its boiling point, and doesn’t lose heat too fast. Wait for a minute or two after the water is freshly boiled before pouring over coffee grounds.

Too Much Hassle?

Pouring water into a coffee machine's water tank
With a coffee machine, simply refill the water tank with water and the machine does the work for you. Featuring the De’Longhi Maestosa Fully Automatic Coffee Machine. Photo from De’Longhi.

No time to take note of all the details above? De’Longhi’s range of coffee machines has you covered. Save the hassle of boiling water from scratch and figuring out how much water you should be using.

From the bean to the cup, all you have to do is pour filtered water into the machine and the machine will do the rest of the work for you. Ready to get your hands on a coffee machine? Shop here.