The latest guidelines issued regarding the Appropriate Quantity of Oral Fluid intake state that:

Healthonics, Chronic dehydration

In a person leading a sedentary life style, 2000ml-2500ml [2litres-2.5 litres] of oral fluids is the appropriate quantity of oral fluids to be consumed per day.

This is a revision from the prior guidelines which advocated that 3000ml-3700 ml [3 litres -3.7 litres] of oral fluids should be consumed per day. [National Academies of Medicine Guidelines]

The update also mentions clearly that more fluids may be consumed by persons involved in heavier physical activities.

The Dictum to be followed while deciding the proper Fluid intake for oneself is

“ Let Thirst guide your Fluid intake”