Total Dissolved Solids in Water

A total dissolved solid (TDS) is a measure of the combined total of organic and inorganic substances contained in a liquid. This includes anything present in water other than the pure H20 molecules. These solids are primarily minerals, salts and organic matter that can be a general indicator of water quality. High TDS generally indicate hard water, which can cause scale build up in pipes and appliances. Scale buildup reduces performance and adds system maintenance costs.

As we learned previously, many dissolved inorganic water contaminants or impurities exist as ions in solution, the most common of these ions are:

These electrically charged dissolved particles make ordinary natural water a good conductor of electricity. Conversely, pure water has a high electrical resistance, and resistance is frequently used as a measure of its purity.

Cations Anions Calcium Ca+ + Bicarbonate HC09 Magnesium Mg++ Chloride Cl Sodium Na+ Sulfate SO,- Iron Fe+ + Nitrate NO, Manganese Mn+ + Carbonate CO,_ _

Since only a few of these most common ionic water contaminants are health related, most natural water supplies are safe to drink from the standpoint of dissolved inorganic chemical contaminants. However, even though found more rarely - and in much smaller quantities - certain inorganic ions can be toxic. Turbidity and bacteria are examples of suspended water contaminants.