How water quality for coffee affects flavour

Esther Gibbs
October 4, 2023
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One variable that is often forgotten in daily practice, yet can significantly affect flavour, is the water quality for coffee. This is particularly true when it comes to quality control in a coffee roastery. 

While specialty coffee roasters spend ages sourcing high-quality beans, a cup of coffee is 98% water. For espresso, it is closer to 90%. So, inferior water quality can ruin the beverage regardless of how the coffee is grown, processed, or roasted. 

Therefore, specialty coffee roasters need to consider the quality of the water within their roastery, particularly when testing coffee. Additionally, they need to factor in the composition of the water their customers are using. More so, they must consider how to advise consumers on the importance of water quality for coffee.

To learn more about water quality for coffee, I spoke to Kasjan Orzol, the host of ‘The Roaster’s Podcast’, which has an episode dedicated to coffee roasting and water in coffee. 

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Understanding the composition of water quality for coffee

“Chemistry in water has a huge impact on how the coffee is brewed,” explains Kasjan, who is also the coffee technical manager at GAIL’s Bakery in the UK. “It’s not that one is right while the other is wrong, it’s just different. It’s challenging to brew a good cup of coffee if you don’t have the right water for it.”

The guidelines by the Specialty Coffee Association (SCA) state water in coffee should be fresh and free from odours, colours, and chlorine. Additionally, the total hardness of the water should be between 50 and 175 ppm of CaCo3. The carbonate hardness of the water should be between 40 and 75 ppm CaCO3, with a PH of between 6.5 and 7.5. Water that matches these specifications can protect equipment and determine how well the coffee extracts. 

For instance, Kasjan explains using hard, unfiltered water to brew a medium roast coffee may make it taste closer to a darker roast. “The cup will suddenly feel heavier, less clean, less elegant. Your flavour notes might shift from chocolate to dark chocolate, from nuts to roasted nuts. You may even lose many of the aromatic enzymatic floral and fruity characteristics of the coffee,” he says.

Alternatively, when softer water is used in the brew, the coffee may taste more sour or underdeveloped as it doesn’t have the buffer of hard water. 

“The carbonate hardness, or alkalinity/temporary hardness is about how many bicarbonates are in the water,” Kasjan says. “These bind to the acids and equalise the PH. If you have water with a lot of bicarbonates, it will mute the acidity. So, your highly acidic and bright coffee will suddenly feel flatter and less acidic.

“If the water you are using to quality check your roasts has high alkalinity, then you might end up with coffee that, in any other water, might seem a little bit too acidic, sharp, and sour.” 

Interestingly, specialty coffee roasters who use water with low levels of alkalinity for brewing and quality control may experience a longer development time. This is to try to decompose the organic acids as much as possible, as the acidity will be heightened due to the water composition. 

This could lead roasters to bake the coffee and extend the development time too much in an attempt to reduce the harsh acidity and bring in some balance. Of course, when you as a coffee roaster taste it, it is pleasant and enjoyable. However, when other people use water that is within the SCA recommendations, they will experience a flat, baked coffee. 

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Water quality for coffee: Educating consumers

“The water used for your quality control, protocols, and checks all forms part of overall quality management,” Kasjan says. “First and foremost, it’s about being aware of what your water composition is.”

He advises specialty coffee roasters to be mindful of how they filter their water, and educate consumers on how to get the best out of their coffees. For instance, it’s important for customers to regularly change their water filters on at-home espresso machines. This helps to ensure they are brewing the coffee at a standard that replicates that of the roastery. 

“If you are creating your own water system, and nobody else can replicate it, then your customers aren’t going to get the same results,” Kasjan says. “The flavour notes you put on your coffee bag might be unique to your water.” 

He recommends using water titration kits to test the total hardness, calcium hardness, and PH level of the water in the coffee roastery. This should be done weekly to check there is no change in the water. 

If there are changes in the water, coffee roasters can make corrections such as changing filters or adjusting the water composition to correct it. This can save time and mistakes within quality control, which could actually be a change in flavour due to the water rather than the roasting profile. 

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How can specialty coffee roasters ensure quality water for roasteries?

“Whatever water system you choose to use within your roastery, be aware of it, and be consistent with it. Reach for the things that give you the most leverage and best results without needing to do a PhD in water chemistry,” Kasjan says.

Low-quality water can damage machinery and cause other problems relating to brewing and health and safety. Hard water can build up limescale on machines, which can cause blockages and reduce the function of parts like thermostats.

On the other hand, soft water can be too acidic and cause corrosion within the machine, which can lead to boilers exploding or pipes disintegrating. 

Specialty coffee roasters should ensure they are testing coffee with water that falls within the range discovered by supported scientific research> Furthermore, they should educate customers about how the water in coffee can affect the final brew. 

For instance, recommend to homebrewers which water to buy from the local supermarket or a filter that they can use at home. Or, specialty coffee roasters can choose to send out reminders to consumers to test their water and offer advice on appropriate filters. 

Alongside ensuring water quality is optimum for brewing the best cup, specialty coffee roasters must ensure their coffee is as fresh as possible when it reaches the consumer. At MTPak Coffee, we have a range of environmentally friendly packaging that will ensure your coffee can degas without compromising on quality.

Furthermore, we offer custom–printing, allowing coffee roasters to advise consumers on which water is best for their perfect cup. 

For more information on custom coffee packaging, contact our team.

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