Question

why does sometimes tap water smells like chlorine or bleaching powder

Answer 1

the fact that municipal water plants use chlorine to eradicate waterborne germs like e.coli and the novorious

Answer 2

since we get drinking water from many sources like bore well, rivers , etc
so water contains many impurities n microbes
to kill them the water supply dept add chlorine and bleaching powder ..... and provide us pure drinking water