Water pollutant can be classified in to the following categories. Suspended matter Natural organic pollutants Synthetic organic compounds Pathogens Inorganic pollutants Thermal pollutants Radioactive pollutants Sediments Water pollutants can also be classified in general on the basis of physical nature as: Suspended particles These particles have diameter of more than 1 micrometre and are the largest in polluted water. They are large enough to settle out of water quickly and may be retained on the filter. Examples of suspended particles are leaves, soil particles, oil and grease etc. Colloidal particles These particles are so small that their settling rate is insignificant. They cannot be removed by plain sedimentation. They are charged particle, charge can be negative or positive but mostly in water colloidal particles are of negative charge. Dissolved matter This pollutants gets dissolved in the water and does make water turbid, such matter does not settled out or nor can be removed by filter. It can be organic or inorganic.
