There are five main types of water pollution:1. Biological pollution – This is when harmful bacteria, viruses or other organisms contaminate water. This can happen when sewage or animal waste enters waterways, or when stormwater runoff picks up contaminants from the land.2. Chemical pollution – This occurs when harmful chemicals enter water, either from runoff or direct discharge. These chemicals can come from factories, agriculture, mining or even household cleaners.3. Nutrient pollution – This is when water contains too many nutrients, such as nitrogen and phosphorus. This can lead to excessive growth of aquatic plants and algae, which can deplete oxygen levels in the water and harm aquatic life.4. Thermal pollution – This happens when water is heated or cooled by industrial processes, leading to changes in temperature that can be harmful to aquatic life.5. Sediment pollution – This is when soil and other particles suspend in water, making it cloudy and difficult for sunlight to penetrate. This can block the gills of fish and other aquatic animals, and smother plant life.