Sewage and inorganic waste pollute water sources in several ways: 1) Untreated sewage releases bacteria that use up oxygen in water, killing other organisms and potentially spreading disease. 2) Dumping of inorganic wastes like mercury poisoned people through Minamata disease and pollutes waterways. 3) Pesticides and insecticides used in agriculture accumulate up food chains and can poison top predators over time due to bioaccumulation.