Water pollution causes

Water pollution causes inadequate economic development, especially industrial development, and uncontrolled urbanisation.More recently, pollution from agriculture and aquaculture has gained prominence.
Chemical pollution of surface water can create health risks, because such waterways are often used directly as drinking water sources or connected with shallow wells used for drinking water. In addition, waterways have important roles for washing and cleaning, for fishing and fish farming, and for recreation.
Water pollution caused by various factors: heavy metals,organic pollutants,nutrients, microbial contamination, toxic organic compounds, traces of chemicals and pharmaceutical drugs, nuclear waste, salinisation, acidification...
Water, the essence of all living things, covers more than three-quarters of the Earth's surface. Water pollution has serious implications on marine life and human health.Coastal pollution of seawater may give rise to health hazards because of local contamination of fish or shellfish.
Water is a unique substance, because it can naturally renew and cleanse itself, by allowing pollutants to settle out (through the process of sedimentation) or break down, or by diluting the pollutants to a point where they are not in harmful concentrations.
Natural phenomena, such as volcanoes and algae blooms, can create
drastic changes in water quality, water is typically deemed polluted only when impaired by human contaminants.

Water pollution causes pollutants that come from a specific source such as a pipe that discharges used water or other material from a factory into a water body. Such discharges can harm the aquatic ecosystem.
They can also come from large areas such as agricultural fields that have been covered with fertilizer or pesticides.Rain water or melted snow can transfer materials such as oil, litter, fertilizers, and salt down storm sewer inlets found on the streets. In some areas, the storm sewer transports this polluted water to a water treatment facility.