You lose and use water constantly. You lose water when you sweat and urinate, and even when you exhale. It's important to keep your body in equilibrium by replacing water that you expel through drinking plus eating fruits & vegetables that are high in water. Where you get water from is really important in this day and age as there is so much contaminated water out there. Remember when filtering water you are also removing important minerals that are important for your health. Did you know through exercise you can actually restructure the water that you have in your body? Also it has been said the sun can also restructure water in eumelanin beings.
Situations where the body needs more water:
In hot and/or humid climates
When doing physical activity
When feverish
When vomiting
With diarrhoea
When pregnant
When ill
When breastfeeding
When taking certain medications
When you have burns, like extensive sunburns
At high altitude (which causes increased urination and breathing rate)
Those with chronic health issues, the elderly, infants and young children are all more sensitive to dehydration
Signs of dehydration:
No tears
Sunken eyes
Less urine than usual
Dark urine (although this can also be affected by medications, diet and supplements).
Dry mouth
Lack of saliva
Fast heart rate
Cool, dry skin
Fatigue or lethargy
Impaired mental functioning
Sunken fontanel, or soft spot, in infants
Listlessness or coma in severe cases
The amount of water you need depends on many factors, including:
General health
Diet
Age
Percentage body fat
Air temperature
Activity level