The mineral primarily responsible for the hardness of water is calcium carbonate. Hard water contains a higher concentration of minerals, particularly calcium and magnesium ions. When water percolates through limestone and other geological formations, it dissolves these minerals, resulting in hardness. Hard water can cause scaling in pipes and appliances, which may reduce efficiency and lifespan. Despite its drawbacks, hard water can benefit health, as it contains essential minerals. Softening methods, such as ion exchange, can treat hard water for household and industrial use, making it more suitable for various applications.