Answer:

Water hardness is the high amount of dissolve mineral or ions as calcium, magnesium etc in the water.

If i want to use hard water for my textile dye processing,1st i need to make this hard water into soft water through different reactions for good results.

Water can be hard in two ways. They are:

1.Temporary hardness and 

2.permanent hardness. 

Temporary hardness:

Temporary hardness  is caused by calcium or magnesium hydrogen carbonet.For making this  Temporary water to soft water, we have to  boiling this and make by using calcium reaction like

Ca(HCO3)2+Ca(OH)2→2CaCO3↓+2H2O

Mg(HCO3)2+2Ca(OH)2→2MgCO3+2H2O

MgCO3+Ca(OH)2→Mg(OH)2+CaCO3

Permanent hardness is caused by calcium or magnesium sulphate.

CaSO4+Na2CO3→CaCO3+Na2SO4

MgSO4+Na2CO3→MgCO3+Na2SO4

MgCO3+Ca(OH)2→Mg(OH)2+CaCO3

 For above that we can see permanent hardness remove by the chemical treatment  but temporary hardness is remove by both boiling and temporary treatment