After heavy rain, the water from Shreyas's tap comes out muddy

Why

Shreyas used two real separation methods correctly: letting the mud settle is sedimentation, and pouring off the clear water is decantation. Those steps do remove the mud — he is correct that the water is cleaner than before. But they can only remove things that don't dissolve and are heavy enough to sink. Germs are far too tiny to see and many never settle, and substances dissolved in the water stay spread through it — just as salty water looks perfectly clear. Water after floods and heavy rain is especially likely to carry germs. So 'clear' only tells you the mud is gone, not that the water is safe. The safe next step is to boil the water (and let it cool) or use a proper water purifier. Test: dissolve a spoon of sugar in a glass of water — it looks just as clear as plain water, yet it is clearly not plain water. Anvi is right: settling and pouring off removes the mud, but clear-looking water can still carry germs and dissolved impurities, so it should be boiled or purified before drinking.