Drinking 3 litres of water

Isn't 3 liters too much? Or just drink as many as the body needs?

Now a days doctor say please don't do much water as there are chemicals and undissolved materials in it which can lead to kidney disease

I drink water when I am thirsty or before going to an activity that is hot. The amount of water we drink should depend on the climate and temperature of a certain place and the activity we do plus our body mass and weight, learn to listen to your own body, it will tell you when it needs water so there is no fixed formula on how much an individual has to take cause it depends.