Total Hardness Calculator
About Total Hardness
What is Total Hardness?
Total hardness is a measure of the mineral content in water, primarily caused by the presence of dissolved calcium and magnesium ions. It is typically expressed as milligrams per liter (mg/L) of calcium carbonate (CaCO₃) equivalent.
The Total Hardness Formula
The formula used for calculating total hardness is:
Total Hardness (mg/L as CaCO₃) = (Burette Reading × Normality of EDTA × Equivalent Weight of CaCO₃ × 1000) / Volume of Sample
Components of the Formula:
- Burette Reading: The volume of EDTA solution used in the titration (in ml)
- Normality of EDTA: The concentration of the EDTA solution used (typically 0.01N)
- Equivalent Weight of CaCO₃: The equivalent weight of calcium carbonate (50)
- Volume of Sample: The volume of water sample taken for analysis (in ml)
Importance and Significance:
Total hardness in water is significant for several reasons:
- Industrial Applications: Hard water can cause scale formation in boilers, cooling towers, and pipes, reducing efficiency and increasing maintenance costs.
- Domestic Use: Hard water requires more soap for effective cleaning and can leave deposits on fixtures and appliances.
- Water Treatment: Knowledge of water hardness is essential for designing appropriate water treatment processes.
- Agricultural Use: Water hardness can affect soil structure and the availability of nutrients to plants.
Classification of Water Hardness:
| Classification | Hardness Range (mg/L as CaCO₃) |
|---|---|
| Soft | 0-60 |
| Moderately Hard | 61-120 |
| Hard | 121-180 |
| Very Hard | >180 |
Practical Uses of Total Hardness Testing:
- Determining appropriate water treatment processes for industrial and municipal applications
- Evaluating the need for water softening in homes
- Assessing water quality for aquariums and aquaculture facilities
- Monitoring irrigation water for agricultural purposes
- Evaluating compliance with regulatory standards for drinking water
Types of Hardness:
Temporary Hardness: Caused by carbonate and bicarbonate salts of calcium and magnesium, can be removed by boiling.
Permanent Hardness: Caused by sulfates, chlorides, and nitrates of calcium and magnesium, cannot be removed by boiling.
EDTA Titration Method:
The EDTA (Ethylenediaminetetraacetic acid) titration method used for total hardness determination is based on the ability of EDTA to form stable complexes with calcium and magnesium ions. The endpoint is detected using Eriochrome Black T indicator, which changes from wine red to blue when all calcium and magnesium ions have been complexed.
