Water pollution occurs when water bodies, such as rivers, lakes and oceans are contaminated with harmful substances. These substances degrade the water quality and are toxic to humans as consumers and to the environment. The contamination in a river can come from a point source or non-point source pollution. The most common types of surface water pollution are agriculture, sewage and waste water (including stormwater runoff), oil pollution and radioactive substances. The agricultural sector consumes a lot of fresh water and is the leading source for water degradation.