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 micro-organisms in water cause?
Micro-oganisms are the perpetrators of many health effects caused by contaminated drinking water. For example, the bacteria Legionella can cause legionellosis, a lung disease and the cryptosporidium parasite is the cause of gastrointestinal diseases.
Various health effects and their causes are shown in this table:
|Type of organism||Disease||Effects|
|Bacteria||Typhoid fever||Diarrhoea, severe vomiting, enlarged spleen, inflamed intestines; often fatal if untreated|
|Cholera||Diarrhoea, severe vomiting, dehydration; often fatal if untreated|
|Bacterial dysentery||Diarrhoea; rarely fatal except in infants without proper treatment|
|Enteritis||Severe stomach pain, nausea, vomiting; rarely fatal|
|Viruses||Infectious Hepatitis||Fever, severe headache, loss of appetite, abdominal pain, jaundice, enlarged liver; rarely fatal but may cause permanent liver damage|
|Parasitic protozoa||Amoebic dysentery||Severe diarrhoea, headache, abdominal pain, chills, fever; if not treated can cause liver abscess, bowel perforation and death|
|Giardiasis||Diarrhoea, abdominal cramps, flatulence, belching, fatigue|
|Parasitic worms||Schistosomiasis||Abdominal pain, skin rash, anaemia, chronic fatigue, chronic general ill health|
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.