Causes of water pollution

Sewage and waste water

Everyday, we cook, do laundry, flush the toilet, wash our cars and do many things that use water. Think about how we use water in schools, hospitals and public places.

Where do you think all the water, liquid waste, toilet and urine ends up? In many developed communities, all this water and soluble waste (called sewage) is treated, cleaned and dumped into the sea. Even though they are treated, they are never the same as fresh water.
In undeveloped countries, the sewage is not treated, but quickly dumped into the sea or water bodies. This is VERY dangerous because they contaminate the environment and water bodies and bring many deadly diseases to us.
Septic Tanks
Every domestic (home) toilet is connected to septic tank usually located outside the house. Each time poop is flushed down the toilet, it goes into this tank, where the solid part is separated from the liquid part. Biological processes are used to break down the solids and the liquid is usually drained out into a land drainage system. From this stage, it can escape into the soil and nearly water bodies.

Ocean and marine dumping
Again, think of the rubbish we all make each day. Paper waste, food waste, plastic, rubber, metallic and aluminum waste. In some countries, there are deposited into the sea. All these waste types take time to decompose. Example, it is know that paper takes about 6 weeks, aluminum takes about 200 years and glass takes even more. When these end up in the sea, they harm sea animals and cause a lot of deaths

Industrial waste

Industries also cause huge water pollution with their activities. These come from:
Asbestos – This pollutant cancer-causing properties. When inhaled, it can cause illnesses such as asbestosis and many types of cancer.

Lead and Mecury – These are metallic elements and can cause environmental and health problems for humans and animals. It is even more poisonous. It is usually very hard to clean it up from the environment once it get into it because it in non-biodegradable.

Nitrates & Phosphates– These are found in fertilizers, are are often washed from the soils to nearby water bodies. They can cause eutrophication, which can be very problematic to marine environments.
Sulphur – This is a non-metallic substance that is harmful for marine life.
Oils – Oils forms a thick layer on the water surface because they do not dissolve in water. This can stop marine plants receiving enough light for photosynthesis. It is also harmful for fish and marine birds. A classic example is the BP oil spill in 2012 with killed thousands of animals species.
Oil Pollution

Routine shipping, run-offs and dumping of oils on the ocean surfaces happen everyday. Oil spills make up about 12% of the oil that enters the ocean. Oil spills cause major problems, and can be extremely harmful to local marine wildlife such as fish, birds and sea otters and other aquatic life. Because oil does not dissolve, it stays on the water surface and suffocates fish. Oil also gets caught in the feathers of sea birds stopping them from flying. Some animals die as a result.

Underground storage and tube leakages.

Many liquid products (petroleum products) are stored in metal and steel tubes underground. Other sewage systems run in underground tubes. Overtime, they rust and begin to leak. If that happens, they contaminate the soils and the liquids in them end up in many nearby water bodies.

Atmospheric deposition is the pollution of water bodies caused by air pollution. Each time the air is polluted with sulfur dioxide and nitrogen oxide, they mix with water particles in the air and form a toxic substance. This falls as acid rain to the ground, and gets washed into water bodies. The result is that, water bodies also gets contaminated and this affects animals and water organisms.