Water for human consumption must be palatable and safe. Palatable water is pleasant to drink, meaning it is completely clear and free from tastes, odours and colours. Safe drinking water, also known as potable water, is defined as water that does not contain harmful or potentially harmful substances and does not present any risk to human health. Harmful substances can be in the form of micro-organisms or chemicals. Unsafe water is a cause of bad health for people of all age groups. There are, however, some groups of people who are at greater risk. These include infants and young children, older people and people who are debilitated by diseases (such as HIV/AIDS).

Importance of water for human health

Water makes up about 70% of an adult human being’s weight. In the human body, blood contains about 82% water and our brain is made up of about 95% water. Losing just 2% of our water content can result in signs of dehydration, fuzzy short-term memory and difficulty in focusing on smaller print or words displayed on a computer screen.

Water has several roles in relation to human health:

• Water plays an important part in keeping us and our environment clean. It is essential for good personal hygiene. We use water to wash our hands and bodies, and also to wash places in our homes that could possibly harbour harmful micro-organisms (such as toilets).
• Many of our foods are prepared with water and others naturally contain large amounts of water (e.g. milk is made up of approximately 88% water; eggs 66%; fish 80%; potatoes 75%; and beef 77%).
• Inside the body, water serves as a lubricant during digestion of our food. Water in saliva facilitates chewing and swallowing, and the food goes down into the stomach with the help of water. The functions of all the body’s cells and organs depend on water.
• Water is involved in transporting valuable nutrients around the body in the bloodstream. Nutrients are broken down in the digestive system and transported to where they are needed in the body.
• Water is used by the body to remove harmful toxins and wastes through urination and perspiration. Water also helps to reduce constipation. Drinking enough water helps body organs such as the kidneys and the liver to get rid of waste products.
• Water helps to regulate body temperature. The body controls over-heating through perspiration. When sweat evaporates from the surface of the skin, it takes heat from the body and produces a cooling effect.