removal of turbidity

removal of hardness

killing of disease bacteria

complete sterilisation

only (i)

both (i) and (ii)

both (i) and (iii)

only (iii)

applied chlorine

residual chlorine

sum of applied and residual chlorine

difference of applied and residual chlorine

prechlorination

post chlorination

super chlorination

break point chlorination

10 to 15

20 to 25

30 to 35

40 to 50