When to drink water is always in dispute, but Ayurveda explains it clearly in order to digest the food properly and timely. Considering that the water has cold and heavy properties, thus to convert the heavy properties into the light ones, one should boil it, at the same time consuming iced cold water makes the digestive process slow as cold water cools the digestive juices and optimal temperature needed for good digestion.
The best time to drink the regular water is during the meals but not more than a cup, as it helps in the proper digestion of the food.
Drinking water before the food increases Vata(air).
Drinking water especially hot or lukewarm during the food in small quantities increases Pitta(fire) which aides in digestion.
Drinking cold water after the food increases Kapha(earth), above all Kapha people should take more care because of their water retention tendency. People with Kapha constitution should always drink one cup of hot water with food as they tend to suffer from digestive problems, it also helps in loosing weight.
It is recommended to wait for an hour to drink any amount of water after meals.