Understanding the Difference Between Total Dissolved Solids (TDS) and Hardness in Water
Water quality is a critical aspect of various industrial, agricultural, and domestic applications.
Two important parameters used to assess water quality are Total Dissolved Solids (TDS) and hardness.
While both measurements provide valuable information about water composition, they address different aspects of water quality.
Very often people think TDS and hardness are the same.
In this article, we will delve into the differences between TDS and hardness, their significance, and the impact they can have on different water uses.
Total Dissolved Solids (TDS)
TDS refers to the total amount of inorganic and organic substances dissolved in water.
These substances can include minerals, salts, metals, ions, and other dissolved particles.
TDS is typically measured in parts per million (ppm) or milligrams per liter (mg/L).
Click to read: How to Check TDS Level in Water
The concentration of TDS in water can vary based on the water source, geographical location, and human activities.
Sources of TDS include natural processes such as the weathering of rocks, as well as human activities like agriculture runoff, industrial discharges, and wastewater effluents.
Click to read: How to Reduce TDS Level in Water
TDS levels are often used as an indicator of water quality, and high TDS values may affect the taste, odor, and overall acceptability of water for consumption.
Hardness
Hardness, on the other hand, is a measure of the concentration of calcium and magnesium ions in water. These ions are primarily responsible for water hardness and can be present as calcium carbonate (CaCO3) and magnesium carbonate (MgCO3).
Click to read: Difference Between Hard Water and Soft Water.
Hardness is usually expressed in milligrams per liter (mg/L) or grains per gallon (gpg).
The hardness of water can be classified into two types: temporary hardness and permanent hardness.
Click to read: How to convert Hard Water to Soft Water
Temporary hardness is caused by the presence of bicarbonate ions (HCO3-). It can be removed by boiling the water, while permanent hardness is due to the presence of non-carbonate ions and requires the use of water softeners for reduction.
Click to read: How to Check the Hardness of Water
Differences Between TDS and Hardness
| Criteria | Total Dissolved Solids (TDS) | Hardness |
|---|---|---|
| Composition | Includes minerals, salts, metals, and organic matter. | Primarily measures the concentration of calcium and magnesium ions. |
| Measurement Units | Parts per million (ppm) or milligrams per liter (mg/L). | Milligrams per liter (mg/L) or grains per gallon (gpg). |
| Removal Methods | Processes like reverse osmosis, distillation, or deionization. | Boiling for temporary hardness; Water softeners (ion exchange, chemical precipitation) for permanent hardness. |
| Impact on Water Quality | High TDS levels may affect taste, odor, and overall acceptability. | Can lead to scale formation in pipes and appliances, reducing efficiency. |
Understanding these differences is essential for addressing specific water quality concerns and selecting appropriate treatment methods.
Conclusion
In summary, TDS and hardness are two distinct parameters used to evaluate different aspects of water quality.
TDS provides a comprehensive measure of all dissolved substances, while hardness specifically focuses on the concentration of calcium and magnesium ions.
Understanding the differences between TDS and hardness is crucial for selecting appropriate water treatment methods and ensuring water quality meets the desired standards for various applications.
