Water has a dramatic impact on food service operation worldwide and the quality of the water used in any beverage will influence both the success of the end-product, as well as the longevity of the equipment used.

Water forms the ever-important base and foundation for most beverages and even the most expensive coffee will not mask inferior or impure water sources that were not treated properly.

Water is the hidden ingredient in coffee: it makes up around 90-98% of the cup’s contents. If you can taste the difference between tap water and bottled spring water, that difference will also appear in your brewed coffee.

Though completely safe to drink, tap water often has a slight or pronounced chlorine taste due to water treatment. Hard water will also have a dry, clear mineral-like quality from higher than average presence of certain calcium and magnesium ions, while softer water (with lower mineral load) may yield sweeter taste. Another important component is bicarbonates, salts that balance the acidity/alkalinity of the water. Though broadly neutral in taste, they make considerable difference to the flavors perceived in the final brew.

For optimum coffee brewing, water should be close to neutral (pH7), neither acid nor alkaline. The minerals with the biggest effect on our perception of taste are calcium and magnesium, which can be seen in the white deposits from scale formation in our kettles, coffee machines and all household appliances that heat water.

Most bottled water will have a cleaner taste than domestic water. Usually if an off taste is found in water it will also be present in the taste of the coffee. If you aim for consistency in your taste of the coffee it is important to be consistent in the water you use. As roasters, when tasting our coffee, we use specially filtered water free from any flavor taints such as chlorine, as well as turbidity to leave the water crystal clear.

Just be careful not to strip out to much of the mineral content as this will result in a coffee that tastes flat and dull. We do need some minerals as they are part of the chemistry of extracting flavor from the coffee grounds.

Research by coffee standards organizations around the world has resulted in a broad consensus as to the optimum balance of minerals. This may be useful in comparing the bottled waters available in your area.

The Speciality Coffee Association of America suggests the following guidelines for the perfect water to brew your coffee.

Characteristic Target
Odor Clean, fresh, odor-free
Color Clear
Total chlorine 0mg/liter
Total dissolved solids at 180°C – on bottled water this is described as dry residue at 180°C 150mg/liter
Calcium hardness 4 grains or 68mg/liter
Total alkalinity 40mg/liter
pH 7
Sodium 10mg/liter


Chlorides may be listed on the label – these are not the same as chlorine and are not harmful.

Chloride levels in unpolluted water are around 10mg/liter and to affect the taste the level would need to be more than 200mg/liter.

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!