Preparation · Water

The Right Water for Coffee: Espresso and Filter in Berlin

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A filter coffee is about 98 percent water, an espresso about 90 percent. Everything else you do right – good coffee, fresh roast, clean grinder – passes through this one medium. In Berlin, tap water is hard and rich in carbonates, and that costs flavor and reduces the lifespan of your espresso machine. On this page, I'll explain what matters when it comes to water, how to find out your own water values, and which solution fits your setup. — Juan García, Garza Coffee

FundamentalsWhy Water Determines Your Coffee

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Water in coffee is not a neutral background, but the solvent that extracts the aroma compounds from the ground coffee. Pure water without minerals extracts poorly and tastes flat. Water that is too highly mineralized extracts uncontrollably and overpowers delicate notes. Between these extremes lies a narrow range in which a specialty coffee truly showcases what it was paid for.

That's why the same packet of coffee can taste completely different in two kitchens. The bean isn't to blame, but the tap water.

The Two LeversGH and KH: What Water Does to Flavor

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For coffee, two values are particularly important. Both are often expressed in degrees of German hardness (°dH).

General Hardness (GH) is the content of calcium and magnesium. These minerals bind the aroma compounds and give the coffee body and sweetness. Too little GH and the cup appears thin, too much and it becomes chalky.

Carbonate Hardness (KH), also known as alkalinity, is the content of bicarbonate. KH acts as a buffer: it neutralizes acids. A little of it stabilizes the flavor, too much makes the coffee flat and robs it of its fruity, vibrant acidity. In Berlin, precisely this second value is the problem.

Target ValuesIdeal Coffee Water According to SCA

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The Specialty Coffee Association has defined a target range for brewing water. It is the reference that almost everyone in the industry follows.

Value	SCA Recommendation	Target
Total Dissolved Solids (TDS)	75–250 ppm	approx. 150 ppm
General Hardness (GH)	50–175 ppm (approx. 3–10 °dH)	approx. 68 ppm
Carbonate Hardness / Alkalinity (KH)	up to approx. 75 ppm	approx. 40 ppm (≈ 2.2 °dH)
pH Value	6.5–7.5	7.0

Rule of thumb for home use: Filter coffee prefers a general hardness around 2–3 °dH, espresso rather 4–5 °dH. Carbonate hardness should be low in both cases.

BerlinBerlin Water: Hard and Carbonate-Rich

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Berlin is clearly above this corridor. Tap water is officially classified as hard.

• General Hardness: depending on the district, 14 to 25 °dH, which is about 250 to 446 ppm. The SCA target range ends at 175 ppm.
• Carbonate Hardness: depending on the waterworks, between 10.3 °dH (Tegel) and 13.7 °dH (Tiefwerder), i.e., about 184 to 245 ppm. The taste target value is around 40 ppm.

The carbonate hardness in Berlin is therefore approximately four to six times higher than the ideal value. This has two consequences. First, the high bicarbonate buffers away the acidity, making the coffee taste flatter than it should. Second, when heated, limescale precipitates and deposits in the boiler and pipes of the espresso machine. In Berlin, good coffee water is therefore not a subtlety, but the foundation.

TestHow to Test Your Water at Home

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Before you invest in a solution, you should know your own values. There are five ways to do this, from free to laboratory analysis.

Method	Cost	Measures	For Coffee
Analysis by Berliner Wasserbetriebe (by postcode)	free	GH and KH of your waterworks	Mandatory starting point
Test strips	€5–10	GH, KH, pH roughly	quick orientation
Droplet test GH/KH	€10–20	GH and KH individually, precisely	best compromise
TDS meter	€10–15	only total dissolved solids	only for checking osmosis water
Laboratory analysis	€30–80	complete mineral profile	one-time, if you want precision

The Easy Way in Three Steps

1. Start for free. On bwb.de, you can find analysis data by postcode. You enter your postcode and see the general hardness and carbonate hardness of your waterworks. This already tells you that you are in the hard range.

2. Measure at your own tap. A droplet test for GH and KH costs around 15 euros and is the best choice for coffee. The official number is an average for your supply area; your house and pipes can slightly alter the value, and carbonate hardness in particular is crucial.

3. Why a TDS meter alone is not enough. A TDS meter gives you a total number, but not whether the hardness comes from calcium or bicarbonate. For coffee and machines, precisely this distinction is important. As a sole tool, it is misleading.

Filter CoffeeWater for Filter Coffee

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For filter coffee, flavor is paramount, as there is no espresso machine working under pressure that would quickly scale up. However, filter coffee is not entirely free of scale: even the kettle quickly accumulates limescale with hard Berlin water and needs regular descaling. Soft, low-carbonate water therefore protects both flavor and the pot.

For the cup, a moderate general hardness of around 2 to 3 °dH and a low carbonate hardness are ideal to preserve the fruity acidity of a specialty coffee. This makes light roasts taste clearer and sweeter. Berlin tap water often makes them taste dull because the high alkalinity flattens the acidity. A simple pitcher filter or suitable bottled water usually makes a noticeable difference for filter coffee.

EspressoWater for Espresso

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For espresso, you have two problems simultaneously: flavor and limescale. The hot water under pressure quickly dissolves limescale, which then deposits in the boiler, valves, and pipes. Therefore, carbonate hardness is particularly important here.

Machine manufacturers recommend a carbonate hardness below 4 °dH, and for high-quality portafilter machines often even 0 to 3 °dH, to largely prevent limescale. For flavor, a general hardness of around 4 to 5 °dH is suitable. With hard Berlin tap water directly from the tap, neither of these can be achieved; without treatment, you risk a scaled-up machine and a flat shot.

SolutionsFrom Pitcher Filters to Osmosis

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There is a ladder of solutions, from simple and inexpensive to precise and elaborate. Which one is right for you depends on your method, budget, and machine.

Do Nothing or Boil

Boiling does precipitate some limescale, but it hardly changes the general hardness and does not reliably remove carbonate hardness. For good coffee in Berlin, this is not enough.

Pitcher Filters (Brita and similar)

A pitcher filter with an ion exchanger reduces hardness and primarily protects the machine from rapid scaling. It is inexpensive and straightforward. What it doesn't provide is a precisely tuned flavor profile: the values fluctuate with the age of the cartridge. As an entry point and for protecting the espresso machine, it is still useful.

Bottled Water: Reading the Labels

You don't need to test bottled water. In Germany, the mineral analysis is legally stated on the label, in mg/l. For coffee, three pieces of information are important.

Reverse Osmosis (Osmosis)

An osmosis system removes almost all minerals from the water. The result is almost empty water, which you can then precisely remineralize. This gives you full control over GH and KH. The effort and initial cost are higher, but for ambitious espresso setups, it is the cleanest solution.

Remineralizing: Ready-Made Sachets or DIY Mixing

Those who work with empty water, i.e., distilled or osmosis water, add minerals back in a controlled manner. Distilled water is available cheaply in drugstores like dm or Rossmann.

• Ready-made minerals. Sachets like Third Wave Water are pre-mixed for espresso or filter. One sachet goes into about 2 liters of distilled water, shake briefly, and it's ready.
• Mix it yourself (DIY). You prepare two concentrates from Epsom salt (magnesium sulfate) and baking soda (sodium bicarbonate) and then dose them into the distilled water. The goal is a TDS between about 110 and 170 ppm. This method is the cheapest and most flexible but requires a scale and some patience.

RecommendationWhich Solution Suits You

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Filter Coffee Only: A pitcher filter or suitable, low-mineral bottled water is usually perfectly sufficient. No need for an osmosis system.

Espresso with an Entry-Level Machine: A pitcher filter to protect against limescale, plus regular descaling according to the manufacturer's instructions. If you want more from your shot, try remineralized bottled or osmosis water.

Espresso with a High-End Machine: Here, osmosis plus remineralization or precisely mixed water is worthwhile. This protects your investment and provides the cleanest taste.

FAQFrequently Asked Questions

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Is Berlin Tap Water Too Hard for Coffee?

For optimal flavor and for espresso machines, yes. With 14 to 25 °dH general hardness and around 10 to 14 °dH carbonate hardness, Berlin water is significantly above the recommended values. It is perfectly drinkable, but for coffee, treatment is advisable.

How Do I Know How Hard My Water Is?

The quickest way is to check by postcode with the Berliner Wasserbetriebe. More precisely for your tap is a droplet test for GH and KH from an aquarium or coffee supply store.

Is a Brita Filter Sufficient for an Espresso Machine?

It significantly helps protect against limescale. It does not provide a precisely tuned flavor profile because the values fluctuate with the age of the cartridge. For entry-level machines, it is a good compromise.

Can I Use Bottled Mineral Water?

Yes, if the label is suitable. Look for low bicarbonate and moderate values for calcium and magnesium. Very mineral-rich waters are unsuitable for coffee.

What Does TDS Mean and Do I Need a Meter for It?

TDS stands for the total amount of dissolved solids in water. A TDS meter is useful for checking remineralized or osmosis water but does not replace a GH/KH test because it doesn't show the breakdown.

Do I Still Need to Descale My Machine and Kettle?

Less frequently with soft or treated water, but depending on the water and usage, descaling remains advisable. This applies to the espresso machine as well as to the kettle for filter coffee, which quickly scales up with hard Berlin water. Follow the manufacturer's instructions.

AssortmentCoffee from Berlin for Your Water

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When the water is right, these coffees reveal their full aroma. Freshly roasted in Berlin, for espresso and filter.