How does water quality affect coffee?

Have you ever had such an experience in life?

On a sunny and warm spring morning, you come to the store in high spirits, thinking that you must make the perfect cup of coffee today!

Checked the coffee equipment, no problem!

Then grind freshly roasted coffee beans, so fragrant and no problem!

Then the proper water-to-powder ratio for brewing, the skillful operations, no problem!

But as soon as you pour in the coffee, there is an indescribable bitterness/astringency, so what is the problem?

Could be a water issue.

Water makes up 98% of coffee, which means that poor quality water can make coffee taste flat, bitter or vinegary. Not only does it hinder coffee extraction, creating an unpleasant taste, it can also cause serious problems in coffee equipment.


Next, we will explore the relationship between water and coffee from the following 3 aspects:

1. understanding water quality; water affects coffee flavor; 3. seven factors o measure the water quality of coffee.

The Taste of Water


We always understand "water quality" simply as strength (hardness) and body (degree of mellowness), but in fact, water usually has many flavors of its own.

Water may contain minerals, dissolved substances, and even additives, all of which can have an impact on the taste of coffee.


How does water affect coffee flavor? 

Having the right amount of minerals like magnesium and calcium in water can actually help baristas achieve better extractions. Magnesium helps extract a richer and more refreshing taste, while calcium enhances the creaminess.

This is due to the positive charge of their ions. Generally, the flavor compounds in coffee are negatively charged, so they are naturally attracted to the positive charge of minerals such as magnesium and calcium.

How to measure water quality for coffee?


Cafe owners and baristas should know at least the following information:

1. Odor

There should be no odor. This is an olfactory evaluation standard for water.

For example, distinct odors caused by sulfates, bacteria or other microorganisms, chlorine or phenolic compounds should be treated and removed.

2. Color

It should be very clear. This is the visual evaluation standard. Any cloudiness, red or orange color or particles in the water should be dealt with on a case-by-case basis.

3. Chlorine

Should be 0 mg/L. Municipal systems often add chlorine to water to prevent biological contamination (microbes). According to the World Health Organization, the chlorine concentration in most disinfected water is 0.2-1 mg/L (WHO, 2011).

The SCAA's standard is strictly to remove all chlorine from the water, as it has a large potential impact on the coffee's in-cup flavor.

4. Total Dissolved Solvents Total Dissolved Substance Content (TDS)

TDS is the key metric recommended by the SCA for measuring water use in the coffee industry. It should be at 75-250 mg/L, with TDS target value of 150.

TDS measures any minerals, salts, metals or other solids dissolved in water. Mineral concentration in water is an important taste influencer that can have both negative and positive effects depending on the mineral and concentration, and can significantly affect extraction.

5. Calcium Hardness

1-5 grams per gallon (gpg) or 17-85 mg/L. SCA recommends that the target should be 3-4 gpg or 51-68 mg/L.

Water hardness refers to the concentration of specific minerals in the water: calcium, magnesium, iron and manganese, as well as some other minerals in smaller amounts. In other words, water hardness is part of the TDS, and a high TDS usually indicates hard water.

Total hardness is a measure of cations in water, which can be produced by positively charged minerals. The main components of hardness are calcium (Ca++) and magnesium (Mg++) ions. Dissolved iron (Fe++) and manganese (Mn++) also meet the definition of hardness, but usually only make up a small fraction of the total hardness.

The presence of some dissolved mineral material in drinking water is often what gives the water its characteristic and pleasant taste. However, too much can cause excessive deposits to build up on your coffee extraction equipment, creating "scale" (mainly calcium), which can also clog the pipes and prevent the proper flow of water and steam. impair its performance. Therefore, the hardness of the water is the key to the life of the equipment.

So for the cafe owner, it is necessary to replace the filter regularly, increase the maintenance and clean the equipment.

6. pH

pH also plays a vital role in caffeine extraction. We have learned in middle school textbooks that water is neutral if the pH is 7.0, alkaline if the pH is above and acidic if it is below.

In caffeine, the more neutral the water, the better. The SCA recommends coffee with a water pH of 6.5 to 7.5 optimal.

As hydrogen (H+) ions increase, the pH of water decreases, which means it has higher acidity. Water becomes alkaline when there are large amounts of hydroxide (OH-) ions, which can cause the water to have a bitter taste.

Alkaline water (high pH) often results in a flat coffee flavor and eventually limescale.

7. Sodium

Sodium should be less than 30 ml/L with a target of 10 mg/L.

The WHO reports in that most water sodium is below 20 mg/L, but the amount in some countries can exceed 250 mg/L (WHO, 2011). Water softeners can also contribute to the sodium content. Salt can affect the perception of sweetness or sourness in the mouth, so large amounts of salt should be avoided in the water used to brew coffee.

In conclusion, when it comes to coffee extraction, every detail counts, and high-quality water guarantee the quality of coffee and the longevity of your equipment. So, next time you make coffee, you might as well start with water and extract the taste you want!