About 2,5 liters (84,5 oz) is what I usually get recommended to drink. I always thought it seamed a bit "too much". I do believe it is individual, people have different needs, metabolism, sensitivities and how our bodies "hold water". But when I do drink that extra I always feel better. I am easily distracted and can forget to drink water/forget to bring extra water. When I am working I forget time. I put elder flowers in my water yesterday ... that was so refreshing.