Improper Disposal of Sewage
Sewage refers to waste matter that is carried away from homes and industries by sewers(pipes) for treatment or disposal. Sewage includes human waste, dirty water, and even toxic substance such as chemicals.

Sewage must be properly treated to remove toxins before it is discharge into the seas. However, not all places have sewage system. Some places also generate more sewage then their system can habdle, resulting in waste matter that is not treated before it is discharged. Moreover,certain substances such as detergents are non-biodegradable and cannot be removed. These sbstance are eventually discharged into the seas, thus polluting the water there.

Industrial sewage is usually more toxic than sewage from homes because it contains heavy metals such as lead and mercury. Many countries require industries to treat their waste matter even before it is released into the sewers.

















Occurence of Oil Spills
An oil Spill is the accidental release of oil into the seas and oceans by supertankers (very large crude oil carriers). Major oil spills are usually the result of accidents and they can cause much damage. Smaller oil spills (also called leaks) may result from oil rig operation, the painting and cleaning of ships, and the loading and unloading of cride oil.


















Use of Pesticides and fertilisers
Pesticides and fertilisers disturb balance of natural nutrients in the soil and cause water pollution when they are washed by rainwater into streams and rivers.