Water is the most important element for textile dyeing sector. They use water in their every step of dyeing by maintaining  1/8 kg/litter. these water must be soft water.  In most of the textile industries, they collect water from the Underground which  contains a lots of impurities which required to purifying before use.

there are two types of hard water.  - 1.temporary hardness.

                                                               2. permanent hardness. 

1.Temporary hardness: 

Temporary hardness is caused by calcium or magnesium hydrogen carbonate.

So, to make Temporary water to soft water, we can boil this water or take the help of the following reactions:

Ca(HCO3)+Ca(OH)2→2CaCO3↓+2H2O

Mg(HCO3)2+2Ca(OH)2→2MgCO3+2H2O

MgCO3+Ca(OH)2→Mg(OH)2+CaCO3

2.Permanent hardness : 

Permanent hardness is caused by calcium or magnesium sulphate.

So, to make Temporary water to soft water, I can take the help of the following reactions:

CaSO4+Na2CO3→CaCO3+Na2SO4

MgSO4+Na2CO3→MgCO3+Na2SO4

MgCO3+Ca(OH)2→Mg(OH)2+CaCO3