How much water do we need on a daily basis?

Our daily need of water is mainly covered through drinking. On a daily basis we need to drink about 1,5 - 2 litres of water. Foodstuffs that have high moisture contents also contribute to our water supply. With our food we absorb about 1 litre of water a day.
Our total required amount of water is 2,5 litres a day. If we drink enough water and eat enough water-containing food, this should not be a problem.
How much water we drink is determined by our habits, not by thirst. When we feel thirsty, this usually is a sign that we have not been drinking a sufficient amount of water.

Why should we drink so much water?

Water, after oxygen, is the second most important substance for human health. Water is a universal solvent and transport medium, and because of that it is the basis of all biological processes in the human body.
Water is mainly important for the digestive system, because it contributes to the constant supply and export of products and substances. The transport of nutrients can only take place through a solvent, and as such water acts as the main transport medium of nutrients.
Water also attends heat regulation in our bodies. For humans it is of vital importance that the body temperature stays at a standard level. That is why we have to drink water, when we are infected with a fever. Water takes up heat and transports it out of the body while we are transpiring.
We can survive without food for about 30 to 40 days, but we can only survive a few days without water. This is a factor that proves how important water is for us.

What causes humans to become thirsty?

When the human body gives off water the amount of saliva in the mouth will decrease. When our salivary glands give off less saliva, our mouth will become drier. This dryness of the mouth is experienced as thirst.

Why should we not drink seawater?

A long time ago a group of people were shipwrecked, but they had been able to save themselves and now they were floating around on a raft that they had constructed out of wooden boards from the ship that came floating up to the surface. They had no food and no water and they were so far away from the main land that they had no hope of being discovered any time soon.
Because they were very thirsty, life became very hard on the raft after several days. Some of the passengers started drinking seawater in despair. But this made them die of dehydration pretty soon.
How could this have happened while they were drinking water? It happened because seawater contains a lot of salt. When salt enters your body it will absorb a lot of water through a process called osmosis. This will cause the water content of your body to fall, which causes serious dehydration.
That is the main reason why we cannot drink pure seawater and why salt is removed from seawater during drinking water preparation processes.

What health effects do microrganisms in water cause?

Various health effects and their causes are shown in this table:
 

For specific information on health effects of microrganisms, move to the water microbiology FAQ

What is Cryptosporidium?

Cryptosporidium is a parasite that is commonly found in lakes and rivers. It enters water supplies through sewage and animal waste. It causes cryptosporidiosis, a gastrointestinal disease, with people that suffer from damaged immune systems. The largest water systems are now entering a testing program in which they check their source water for Cryptosporidium each month.

Are there any risks to hard water?

For many uses, hard water does not cause any problems. Hard water is not damaging to your health either. In the domestic environment hard water is not very efficient for certain uses: for bathing, washing dishes and clothes, shaving, washing a car, etc.
There are a number of negative effects to hard water, for instance: soap does not mix with hard water very well, when hard water is heated the hardness minerals can plug the pipes and hardness minerals often interfere with industrial processes. That is why hard water is often softened.

Click here for information on general health effects of pollutants on organisms

Click here for the risks and health effects of outdoor swimming

For water terminology check out our Water Glossary or go back to water FAQ overview

In need of some dietary advise? Check out our new vitamin and mineral pages!

Feel free to contact us if you have any other questions