Water pollution occurs when harmful substances enter a water supply, making the water toxic to humans or the environment. Sewage and chemical waste from factories is often dumped into water. Fertilisers used in farming, or minerals from mining can also run into streams. Human and animal waste products contain bacteria which can multiply in water, particularly if the water is stagnant (not flowing).
WHAT ARE THE EFFECTS OF WATER POLLUTION?
Drinking water that contains bacteria can cause disease, particularly diarrhoeal diseases such as cholera. In Africa over 1000 people die per day from diarrhoeal diseases caused by polluted water and poor hygiene. Mineral contamination of water can also be harmful to humans. For example, consuming high quantities of the mineral fluoride through the water supply can lead to weakened teeth and bones.
Water pollution also affects the environment. Toxins can kill plants and animals. Too much fertiliser in water can cause overgrowth of algae. These algae then use up all the oxygen in water so that there is not enough for plants and animals to survive. This is called eutrophication.
In areas where there is no safe water source, families may have to walk long distances to find water to drink. On average, families in rural Africa spend 26% of their time fetching water. Often it is the women and girls who do this, meaning girls are more likely to miss out on education. Carrying heavy containers of water every day can also damage the muscles and skeleton. This increases the risk of arthritis (‘wearing out’ of joints). The long walks for water also put women and children at greater risk of physical and sexual abuse.
HOW CAN WE REDUCE WATER POLLUTION?
You can use natural solutions to make polluted water safer to drink. Ground Moringa plant seeds can be mixed into polluted water to purify it. Water Hyacinths remove harmful minerals from the water they are grown in, and boiling water kills bacteria. Tanks can be used to collect clean rainwater, but these must be emptied regularly to stop water becoming stagnant. Water filtration units are also becoming cheaper and easier to buy. In 2015, Tanzanian Askwar Hilonga won a prize for inventing a water filter that uses sand and small particles to remove pollutants from water.
Government action is also needed to reduce pollution, such as tighter laws to prevent companies dumping waste into water. Reduced use of pesticides in farming will also reduce pollution.
In the city of Uvira in the Democratic Republic of Congo, the government is improving the water services. Studies in Uvira have shown that a lack of clean water supply to houses causes a 2.5x increase in the number of cholera infections. This shows how important a permanent clean water supply is for health. In the future, data like this may motivate businesses and governments to do more to keep water clean.