Calcium is the primary source of hardness in the water. Calcium is found as calcium carbonate or calcium sulfate in the water and precipitates as scale in the equipment, boilers and faucets. This scale can lead to choking of the pipes, decreased efficiency of water heaters and loss of energy.
Magnesium is the second most common source of water hardness. Magnesium is found as magnesium hydroxide or carbonate salt in water. Magnesium behaves in the same manner as calcium, forming brown scale upon precipitation in water boilers, heat exchangers, water pipes and other water related equipment.
Besides calcium and magnesium, there are other elements also responsible for permanent hardness in water. These are iron, lead, salt and aluminum. Mostly, except iron, these elements are found in traces in the water. Water softening treatments which remove calcium and magnesium can remove these trace elements as well.
Clothes washed in hard water often look dingy and feel rough. Continuous laundering in hard water can lead to damaged fibers and shorten the life of clothes. Bathing with soap in hard water leaves a film of sticky soap curd on the skin and may prevent removal of soil and bacteria from the skin. When washing dishes, hard water may cause spotting and filming on the crockery. Hard water also contributes to inefficient and costly operation of water-using equipment and appliances.