Tea Water


The ideal tea water should be soft, rich in minerals, low in chlorine and have a neutral pH value of 7 (although anything between 6-8 might still be considered acceptable). If your water is too hard (i.e. it contains too much calcium and magnesium) you run the risk of developing tea scum in your cup. Tea scum is not harmful, but it does affect the flavor and texture of your brew, the beauty of the tea liquor, and on top of that stains your precious teaware making it harder to clean.

If you live in Trier and receive your water from the waterworks in Irsch, you are in luck, because the water quality is almost ideal for brewing tea (apart from the alkaline pH value of 8.22). The water hardness is ideal and the amount of magnesium is low (high amounts of magnesium make the tea taste over-extracted and metallic in flavor). I advise against using a water filter, since it makes the tea taste flat.

My favorite mineral water to use is Vio (Apollinaris) from the Lüner spring in Lüneburg, but most of the time I stick with tap water, since it is cheaper and reduces unnecessary plastic waste.


Trier (waterworks Irsch) Vio (Lüner source) Ideal
Calcium 22.7mg/L 51mg/L <70mg/L
Magnesium 2.8mg/L 5mg/L  
Hydrogen­ carbonate 68.9mg/L 152mg/L <170mg/L
Potassium 0.7mg/L 0mg/L  
Sodium 4.9mg/L 15mg/L  
Chloride 9.4mg/L 20mg/L 0mg/L
Sulfate 9.1mg/L 19mg/L  
pH value 8.22   6-8
Water hardness 0.68mmol/L 1.51mmol/L >0.2mmol/L<1.5mmol/L

Water Hardness Levels

The water hardness levels are based on the official values of §9 of the Gesetz über die Umweltverträglichkeit von Wasch- und Reinigungsmitteln (Wasch- und Reinigungsmittelgesetz - WRMG)

Hardness level mmol/L
Soft <1.5
Medium 1.5 - 2.5
Hard >2.5