THE human body loses a lot of water through our nose, lungs and during heavy perspiration, especially on a warm day.
Water is also used up in the digestion process that goes on throughout the whole day after having the three meals. It is used up in the body's chemical processes and also in the requirements of maintaining our blood pressure, which contributes to the hydrostatic pressure within the blood vessels.
Our body is composed of about 60 per cent water. The functions of these bodily fluids include digestion, absorption, circulation, creation of saliva, transportation of nutrients, and maintenance of body temperature.
An adequate water intake is essential to keep the kidneys working well, helping them to remove waste products and excess nutrients mainly via urine.
CWM Hospital head of Intensive Care Unit Dr Vereniki Raiwalui says that with that whole process in 24 hours, we would require something from about four to six litres of water for all body processes.
He said we could only consume less than that — about three to four litres a day —and given the whole body processes that require water, we would require up to about four to five litres.
Sometimes, a normal healthy adult living in a temperate climate for men is roughly 3 litres (about 13 cups) of total beverage and for women is 2.2 litres (about 9 cups) of total beverages a day.
The European Hydration Institute also listed the remarkable benefits of hydration on the body, in that it is vital for the proper functioning of the brain and the heart; transportation of minerals, vitamins, nutrients and oxygen to the cells; proper flow of digestion processes; keep the kidneys working well; acts as a lubricant for muscles and joints; and it helps regulate overall body temperature.
Meanwhile, Dr Raiwalui has advised the public to consume water depending on certain conditions and its requirement.
In some medical conditions such as cardiac failure, chronic liver failure and those with kidney failure, they have to be careful and not drink too much fluid. Same for patients on dialysis, they have an intake of a certain amount of fluid requirements.
"For those whose kidneys are failing, and they cannot process fluid quickly in 24 hours, you would have to drink a certain amount, only about a litre. If you do not do that, you get fluid overloaded."
And there are climatic aspects of water consumption.
Hot or humid weather can make you sweat and requires additional intake of fluid.
Heated indoor air also can cause your skin to lose moisture during wintertime.
Further, altitudes greater than 8200 feet (2500 metres) may trigger increased urination and more rapid breathing, which use up more of your fluid reserves.
"Sometimes, towards the end of the year, people working on the roof are told to get off between a certain times because of the extreme heat exposure on the roof. Some people get really severe heat exhaustion, that they have collapsed, even those as young as 23 years old can have a heart attack because of severe heat exhaustion and the severe loss of fluid.
"The other condition is where you are in an enclosed space. So in an earthquake where there is a collapse, you lose quite a lot of fluid because you are in a confined space."
Dr Raiwalui said drinking a huge amount of water could be injurious to the body.
"You have what is required for the body and then you have medical conditions where you have to be careful about taking water. And then you have conditions that if you do not take water, you could suffer a whole lot of complications."