A QUICK CHEMISTRY LESSON

If all this is not quite crystal clear yet, don’t panic!

Here are a few simple pointers on the subject of water hardness and pH.

What is water hardness?

When you bring water to a boil in a pan, the temporary hardness (KH) is lost and shows up instead as white limescale deposits around the sides of the pan. This is because bicarbonates of calcium and magnesium in the water are precipitated out as carbonates on application of heat.

Permanent hardness is the hardness that remains in the water after boiling. It refers to the concentration of sulfates of calcium (gypsum) and magnesium.

The temporary hardness and permanent hardness can be added together to give the total hardness (GH). This is the figure usually indicated by the water company.

Total hardness (GH) = temporary hardness (KH) + permanent hardness. Hardness is expressed in “German degrees”: °dH.

TOTAL HARDNESS = PERMANENT HARDNESS + TEMPORARY HARDNESS

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GYPSUM STAYS IN THE WATER AFTER BOILING

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CALCIUM SHOWS UP AS WHITE DEPOSITS ON THE SIDES OF THE PAN AFTER BOILING

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GYPSUM PASSES THROUGH PIPING, SO IT IS NOT A PROBLEM FOR COFFEE MACHINES BUT IT DOES IMPART A PARTICULAR TASTE TO THE WATER.

What about the pH?

The pH (potential of hydrogen) is used to define, on a scale of 1 to 14, whether water is acidic, alkaline, or neutral:

• If the pH < 7: the water is acidic.

• If the pH > 7: the water is alkaline.

• If the pH = 7: the water is neutral.

The mineral content of the water affects its pH; the higher the mineral content, the higher its pH level; the softer the water, the more acidic it is.

To protect machines from corrosion, the pH should not be allowed to go below 6.5.

TESTING YOUR WATER!

You can measure the properties of your water (KH and pH) using a water test kit for aquarium owners. Some espresso machine manufacturers also sell kits for measuring the hardness of your water yourself.

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