Hard water - water which contains minerals like calcium and magnesium ions (caused by their presence) - these dissolve into the water as it flows through soil and rocks after rainfall.
These ions present in water are not removed during tge water treatment processes as they are dissolved in the water.
To ensure tests are fair:
Same volume of water sample
Shake for same length of time
Sane volume of soap (lather method)
Method can be inaccurate (lather method):
Lather quickly disappears
Difficult to ensure consistent shaking
Comparing results before and after boiling each sample also allows identification of permanent or temporary hardness.
ADVANTAGES
Magnesium and calcium ions are beneficial for health of heart (lowers risk of heart disease) and development of strong bones and teeth.
Improves brewing and baking.
Better taste.
DISADVANTAGES
Firms limescale in appliances - can slow down transfer of heat do less efficient - greater energy cost.
