With test strips from the pharmacy or drugstore for under 10 euros. Alternatively, your local water authority provides figures for your zip code. For a more precise measurement, use a TDS meter, which shows the mineral content in ppm.

How do I measure water hardness myself?

With test strips from the pharmacy or drugstore for under 10 euros. Alternatively, your local water authority provides figures for your zip code. For a more precise measurement, use a TDS meter, which shows the mineral content in ppm.

Why that is

Before you invest in a water filter, you should know what’s coming out of your tap. Water hardness varies wildly across Germany — from under 4 °dH in parts of the Black Forest to over 20 °dH in Berlin and large parts of Northern Germany. If you live in a soft water region, you might not even need a filter.

Test strips are the simplest method. You hold the strip briefly under running tap water and compare the color change to the provided scale. The accuracy is good enough to tell whether you’re in the hard, medium, or soft range. You can get them in pharmacies, drugstores, or aquarium supply shops for under 10 euros a pack.

Water authority data is more precise. Almost every water provider in Germany publishes their analysis reports online — searchable by zip code. There you’ll find the total hardness (in °dH or mmol/L), carbonate hardness, pH level, and often chlorine content. The catch: these figures represent the water as it enters the building. Old pipes or house plumbing can alter the actual values slightly.

TDS meters (Total Dissolved Solids) measure the total concentration of dissolved solids in ppm (parts per million). They cost starting around 10–15 euros and provide a quick overview. For coffee, TDS values are particularly useful when experimenting with water recipes (like Third Wave Water or DIY mixes). The catch: TDS tells you nothing about the composition — the device can’t tell whether the minerals are calcium, magnesium, or sodium.

For most home users, a combination of looking up the water authority data and confirming it with a test strip is perfectly sufficient. If you want to hit the SCA ideal range (50–175 ppm total hardness, 40–70 ppm carbonate hardness) with dead accuracy, you’ll need to invest in a TDS meter and detailed titration drop tests for both carbonate and total hardness.

In practice at Green Wall Coffee

At Sophienstraße 27, we regularly measure our filtered water with a TDS meter — aiming for 90–120 ppm. For guests looking to improve their coffee at home, I recommend this first step: enter your zip code on your local water provider’s website and check the hardness. In Berlin, it’s almost always over 14 °dH — a clear-cut case for a water filter.

Related questions

• What is the ideal water hardness for coffee?
• How important is water quality for good coffee?
• Do I need a water filter for my coffee machine?

You can find more in-depth information in the article How to make perfect espresso. Or drop by Sophienstraße 27 — Mon–Fri 8am–5pm, Sat 10am–5pm.