The hardness of water is determined by the amount of dissolved calcium and magnesium present. The "hardness" is measured in grains of hardness per gallon of water. Hard water in the home makes it difficult to lather soap and can be harmful to pipes and plumbing fixtures. High levels of calcium can not only make the water very hard it can also raise pH.
Method 1 - Hardness Tape
1. Obtain a test strip from teacher.
2. Hold strip in water for five (5) seconds.
3. Immediately read on comparator to find grains per gallon (gpg).
4. Multiply number by 17.1 to find parts per million (ppm).
Method 2 - Hardness Kit
1. Rinse sample bottle 3 times, then fill to 5mL.
2. Add 5 drops of buffer solution and swirl.
3. Add 1 drop of calmagite (purple) solution.
4. Add drops from syringe until solution becomes purple.
5. Add one more drop from syringe to turn solution blue.
6. Using the number on the syringe, mulitply by 300 then divide by 17.1 This will give you an answer in grains per gallon. (Your Outdoor School teacher will help with this test).
How Hard is the Water?
Grains Per
Gallon
Miligrams
Per Liter (mg/l)
or Parts Per
Million (ppm)