The colour in water signals the presence of dissolved or colloidally dispersed organic matter of unknown composition augmented colloidal iron or manganese. Raw water contains bicarbonates in amounts dependent on their origin. Often, water may contain small amounts of carbonate alkalines. The number of bicarbonate and carbonate ions present may be isolated by titration using phenolphthalein as an indicator and methyl orange as an indicator in the second stage. Hardness of water.
Water hardness is caused by calcium and magnesium salts.
Other contributing elements to hardness include metallic ions such as iron and strontium. Note that if metallic ions are present they will be found in minute quantities compared to salts. Hardness can be measured when a given amount of potassium palmitate or oleate solution is titrated using a given amount of water, concluding when the shaken liquid produces a permanent lather. More sophisticated methods are now available where the concentrations of calcium and magnesium ions are quantified by titration with ethylene diaminetetra-acetic acid. Hardness is expressed in degrees, but the actual units of measure vary from country to country.