What is "TDS"?

Lets first of all discuss what TDS is. TDS is an abbreviation for Total Dissolved Solids in a liquid, including organic and inorganic substances in a molecular, ionic, or micro-granular suspended form. TDS is generally expressed in parts per million (ppm) or as milligrams per litre (mg/L). TDS is directly related to quality of water i.e., the lower a TDS figure, the more pure the water. As an example, reverse osmosis purified water will have a TDS between 0 and 10, whereas tap water will vary between 20 and 300, depending on where you live in the world.

The materials that constitute dissolved solids in water include materials such as minerals, salts, anionic and cationic substances. They can also include pollutants such as heavy metals, and other substances such as organic materials that may have leaked into your water supply system.

So where do such materials come from?

Sources can include the following;

• Leaves, silt, industrial waste and sewerage.
• Metals or plastics from corroding pipes (including lead and copper) delivering water from its source to its supply.
• Runoff from areas including fertilizers and pesticides used on farms and in the home garden, which contaminate the ground carrying water or pipes.
• Inorganic materials including rocks and air which may contain nitrogen, iron, phosphorus, sulphur, bicarbonates and other materials, which react with metals to form salts. The salts usually dissolve to form negatively charged (anionic) and positively charged (cationic) soluble particles.