The Importance of Water
Water is continually lost through the normal bodily functions of urination, excretion, breathing and sweating. The amount of water lost through sweating dramatically increases when in hot conditions or during any kind of physical activity.
The greater the exertion the more you lose. So it is vital to keep topped up by sipping regularly rather than gulping large quantities with long periods of time between.
2lt should be the daily consumption of an adult and you should take on more when working hard. It is interesting to note that most backpackers are dehydrated more during winter activity than summer!
During a long backpacking trip you need to be aware that you could need as much as 6 litres per person. 2-3lt to drink, 2lt to wash, clean your clothes, or yourself and another 2lt for cooking, brews etc.
So it is vitally important to be aware of your water sources, contamination and purification as you travel through unknown territory.