Whether we should boil water before drinking depends upon the quality of water we are drinking. You can ask your local city departement about the risks of local water before consuming that. Some people also prefer water filters and think that it is better to filter water than to boil it. Some time filter might leave some bacteria which can later lead to diseases. Boiling water usually will kill all the bacteria but it will also finish useful minerals like calcium from water. So boil the water if it is really needed and if its not healthy.