Permanent Hardness of Water vs. Temporary Hardness of Water

Attribute	Permanent Hardness of Water	Temporary Hardness of Water
Definition	Hardness caused by the presence of dissolved calcium and magnesium ions that cannot be removed by boiling.	Hardness caused by the presence of dissolved calcium and magnesium bicarbonate ions that can be removed by boiling.
Source	Naturally occurring minerals in the water source.	Temporary hardness is usually caused by the presence of calcium and magnesium bicarbonate ions in the water source.
Removal Method	Requires water treatment processes such as ion exchange or reverse osmosis.	Can be removed by boiling the water or by adding lime or soda ash.
Effect on Soap	Forms soap scum or precipitates with soap, reducing its effectiveness.	Does not form soap scum or precipitates with soap, allowing soap to lather easily.
Effect on Plumbing	Can cause scale buildup in pipes and appliances, reducing their efficiency and lifespan.	Does not cause significant scale buildup in pipes and appliances.

Introduction

Water is an essential resource for all living organisms, and its quality is of utmost importance. However, not all water sources are the same, and one aspect that differentiates them is water hardness. Hard water contains dissolved minerals, primarily calcium and magnesium ions, which can have various effects on our daily lives. Hardness can be classified into two types: permanent hardness and temporary hardness. In this article, we will explore the attributes of both permanent and temporary hardness of water, highlighting their differences and implications.

Permanent Hardness of Water

Permanent hardness of water refers to the hardness that cannot be removed by boiling. It is caused by the presence of dissolved sulfates, chlorides, and nitrates of calcium and magnesium. These minerals are usually present in the soil and rocks that water comes into contact with during its journey to our taps. When rainwater or surface water percolates through these geological formations, it dissolves these minerals, resulting in permanent hardness.

One of the main characteristics of permanent hardness is that it remains even after boiling the water. Boiling only removes temporary hardness, as we will discuss later. The presence of permanent hardness can lead to several issues. For instance, it can cause the formation of scale or limescale in pipes, appliances, and heating systems. This scale buildup reduces the efficiency of these systems, increases energy consumption, and shortens their lifespan. Additionally, permanent hardness can interfere with the lathering ability of soaps and detergents, making it harder to achieve a satisfactory level of cleanliness.

To combat the problems associated with permanent hardness, water softening techniques are employed. These techniques involve the use of ion exchange resins or lime softening processes to remove the calcium and magnesium ions responsible for hardness. Water softeners replace the calcium and magnesium ions with sodium ions, effectively reducing the hardness of the water. However, it is important to note that excessive sodium intake may not be suitable for individuals on a low-sodium diet, and therefore, alternative methods like reverse osmosis or distillation may be preferred.

Temporary Hardness of Water

Temporary hardness of water, as the name suggests, can be removed by boiling. It is caused by the presence of dissolved bicarbonates of calcium and magnesium. These bicarbonates are formed when water comes into contact with limestone or chalk deposits, which are rich in calcium carbonate. The carbon dioxide in the water reacts with the calcium carbonate, forming soluble bicarbonates.

When temporary hard water is heated, the bicarbonates decompose, releasing carbon dioxide gas and forming insoluble carbonates. These carbonates precipitate out of the water, resulting in a decrease in hardness. This phenomenon is why temporary hardness can be eliminated by boiling the water. However, it is worth noting that boiling water does not remove any other impurities or contaminants present in the water.

Temporary hardness does not pose the same challenges as permanent hardness. It does not cause significant scale buildup or interfere with soap lathering. However, it can still leave behind a residue or film on surfaces, such as dishes and glassware, which can be undesirable. Additionally, temporary hardness can affect the taste of water, giving it a slightly bitter or chalky flavor.

Similar to permanent hardness, temporary hardness can also be treated through water softening techniques. However, in the case of temporary hardness, boiling the water is often sufficient to remove the hardness. Alternatively, using water filters or adding certain chemicals, such as lime or soda ash, can also help reduce temporary hardness.

Conclusion

Water hardness is an important aspect to consider when it comes to the quality and usability of water. Permanent hardness, which cannot be removed by boiling, is caused by dissolved sulfates, chlorides, and nitrates of calcium and magnesium. It can lead to scale buildup, reduced efficiency of appliances, and interference with soap lathering. On the other hand, temporary hardness, which can be removed by boiling, is caused by dissolved bicarbonates of calcium and magnesium. It may leave a residue on surfaces and affect the taste of water. Both types of hardness can be treated through various water softening techniques, depending on the specific minerals present and individual preferences.