Water and coffee - what influence does water hardness have on the taste of your coffee and what is the optimum water hardness for espresso & co.?

Water portafilter machine unbound

Imagine you're making coffee in two different places. You have exactly the same setup and the same coffee beans - and yet the coffee tastes different? One of the reasons for this could be water hardness. But what is water hardness and how does it affect the taste of your coffee? 

Water hardness - a German matter 

The unit of measurement for water hardness is the designation °dH, i.e. degrees of German hardness. Water below 8.4° dH is considered "soft", the average degree of hardness is 8.4-14° dH, and hard water is anything above 14° dH. 

Tyrolean water

Is hard water the same as calcareous water? 

In everyday life, hard water is often equated with water containing lime. However, there are many more minerals dissolved in drinking water that also influence water hardness. The most important of these are calcium and magnesium ions, which are dissolved in the water. The higher their proportion, the "harder" the water.

Lime only comes into play when the water is heated. There, the calcium and magnesium ions form lime that is difficult to dissolve.

How can I determine the water hardness at my home?

There are several ways to do this. On various online portals, you can find out the hardness level of your municipality using your zip code. If this is not possible for your home or if you want to know exactly, you can purchase free test strips and easily measure the water hardness yourself (e.g. from Brita).

We have compiled a few values for you so that you can roughly estimate how "hard" or "soft" the water is in your area:

  • Innsbruck: 4-6° dH (soft)
  • Wattens: 5-9° dH (soft to medium)
  • Thaur & Birgitz: 18° dH (hard)
  • Schwaz: 15-20° dH (hard)
  • Vienna (Inner City): 13° dH (hard)
  • Bregenz: 12° dH (hard)

The differences in water hardness, by the way, are caused by different soil and rock conditions through which the groundwater flows.

Water glass unbound

So how does the hardness of water affect the taste of your coffee? 

Coffee is 99% water, so of course it's clear that this main ingredient has a major impact on taste. Coffee made with hard water often tastes one-sided and flat, the complexity is lost. Lime prevents the aromas from developing and neutralizes the flavor-building coffee acids (for more information about the aromas in coffee, see this blog). This is why fine nuances such as citrus, fruity and floral notes - which are what make your specialty coffee so special in the first place - cannot develop and come to the fore sufficiently. By the way, this applies to the same extent to high-quality teas.

Bitter tastes can also be a result of water that is too hard. However, other aspects are also decisive for a bitter aftertaste. 

Water hardness affects not only the taste but also the appearance of your coffee. For example, a thin, greasy film tends to form on an Americano or filter coffee when the water is hard.

The softer the water, the better the coffee?

Unfortunately, this is not quite true either. Too soft water leads to too high an acid intensity. The optimum degree of hardness is therefore 6-8° dH.

Life is hard - but that doesn't mean your coffee water has to be, too:

So water hardness is not a modern barista trend, but an important cog for your perfect coffee enjoyment.

Coffee from the portafilter unbound

Not only bad for the taste - hard water also harms your equipment 

Limescale builds up in your coffee maker, as well as in other household appliances, and in addition to changes in taste, leads to incrustations in the piping, increased cycle time, and increased noise.

Here goes to our coffees:

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