What component of hard water makes it hard?

Question

What component of hard water makes it hard?

Answer 1

It is the dissolved solids and minerals make the hard water hard.

The common salts which make the water hard are calcium, magnesium and iron salts. Some waters have high fluorine contents.

The netsearch shows the following details :

Hard water is a type of water that has high mineral content (in contrast with soft water). Hard water primarily consists of calcium (Ca2+), and magnesium (Mg2+) metal cations, and sometimes other dissolved compounds such as bicarbonates and sulfates. Calcium usually enters the water as either calcium carbonate (CaCO3), in the form of limestone and chalk, or calcium sulfate (CaSO4), in the form of other mineral deposits. The predominant source of magnesium is dolomite (CaMg(CO3)2). Hard water is generally not harmful.

The simplest way to determine the hardness of water is the lather/froth test: soap or toothpaste, when agitated, lathers easily in soft water but not in hard water. More exact measurements of hardness can be obtained through a wet titration. The total water 'hardness' (including both Ca2+ and Mg2+ ions) is read as parts per million or weight/volume (mg/L) of calcium carbonate (CaCO3) in the water. Although water hardness usually only measures the total concentrations of calcium and magnesium (the two most prevalent, divalent metal ions), iron, aluminium, and manganese may also be present at elevated levels in some geographical locations.

Answer 2

Hard water varies by source, but the "hardness" is primarily caused by molecules of calcium and magnesium in the water.

Answer 3

i thought it was just minerals in general that made hard water hard, but probably calcium is one of them.

Answer 4

Hard water is water containing a high level of calcium, magnesium, and other minerals. Hard water reduces the cleansing power of soap and produces scale in hot water lines and appliances.