The Total Dissolved Solids Breakdown
TDS is a cumulative parameter of water quality. It encompasses all inorganic and organic substances—minerals, salts, metals, cations, and anions—dissolved in water. While water hardness specifically measures calcium and magnesium, TDS measures everything from potassium and chloride to bicarbonates and sulfates.
Application in Water Filtration
TDS is the primary indicator of effectiveness for Reverse Osmosis (RO) systems. If your tap water has a TDS of 400 ppm, a properly functioning RO system will reduce it by 90-95%, giving you filtered water with a TDS of around 20-40 ppm. If you see your TDS creep up, it’s an immediate signal that your RO membrane needs replacement.
TDS and Equipment Longevity
In commercial kitchens and industrial boilers, high TDS is the enemy. Dissolved solids eventually precipitate and form scale on heating elements, significantly reducing energy efficiency and leading to mechanical failure. This is why water softeners and filtration systems are standard equipment in steam irons, espresso machines, and boiler plants.
TDS Concentration Standards
| Level (ppm) | Rating | Description |
|---|---|---|
| 0 - 50 | Excellent | Purified water (Distilled, RO). |
| 50 - 150 | Good | High-quality natural water. |
| 300 - 500 | Fair | Standard tap water (WHO limit). |
| > 1,000 | Poor | Brackish / Inedible without treatment. |
Related Science Utilities
Frequently Asked Questions
What is TDS?
TDS stands for Total Dissolved Solids. It is the measure of everything dissolved in water that is not a water molecule itself, such as salts, minerals, and organic matter.
Is a high TDS level bad?
A high TDS level can affect the taste of drinking water and indicate the presence of impurities. However, some TDS is natural and necessary for healthy water (e.g., mineral water).
How is TDS measured?
TDS is measured in mg/L (milligrams per liter) or ppm (parts per million). Digital TDS meters estimate TDS based on electrical conductivity.