LaMotte method to test hardness

The LaMotte method for testing water hardness uses a simple titration process to measure how much calcium and magnesium (the minerals that cause hardness) are in the water.

First, collect a water sample in a test tube. Then, add a hardness reagent (usually in powder or tablet form) that causes the water to turn a specific colour.

Next, slowly add drops of a titration solution while swirling the sample. Count each drop as you go.

When the water changes colour, stop. The number of drops used tells you the hardness level in parts per million (ppm) of calcium carbonate (CaCO₃).