"Out of sight, invisible and dissolved in water, TDS what you cannot see."
If a glass of water is held up and it is colourless, crystal clear and has no odour would you think there is much wrong with the water? Total Dissolved Solids (TDS) are completely dissolved in a water supply and generally invisible to the human eye. They are not associated with a bacterial test and are not tested for at the Public Health Unit when you submit a water sample. At certain level’s they pose a risk and are not a recommended drinking water source according to the Canadian Drinking Water Guidelines.
Sometimes what you do not see can be a risk.