How much water should quench my thirst?

Thirst is a natural urge which is so routine that we sometimes forget it's significance in our survival. All the animals crave for water and this forms the fundamental requirement for the survival of almost all the species on this planet. The question of why we feel thirsty could be address by the simple biochemistry at work in our body. Basically we need water to carry various reaction or act as a milieu for cells. Cells in our body are membrane bound structures through which water can pass easily subjected to same concentration of osmolites. If the fluid volume decreases, it will consequently increase osmolite concentration which will squeeze water from cells. In reverse circumstances if the fluid volume is high the cells would swell. Thus, a normal narrow rang of volume needs to be maintained for life to carry on. So the next question becomes, How does our body sense this ? What are the underlying mechanisms? Questions regarding regulation of water volume began as early as 1898 by Tigerstedt and Bergman, with the experiments leading to discover of Renin-angiotensin system. At a hormonal level, Angiotensin II stimulates release of Anti-diuretic hormone which stimulates thirst in the individual which is necessary to maintain the fluid balance of the body.

More recently, It has not escaped the curiosity of two groups which found curious observations in their experiments regarding thirst.
I have observed that I have to drink water before sleeping. The pre-emtive need for water was the subject of this study.

In another study drinking water while eating was the question which was explored. One of the most interesting line of thought is as to why our thirst is quenched when we even sip the water. The water  does not enter the bloodstream so quickly for body to signal the brain of its volumetric balances.