How do these activities result in pollution of water?
Sewage from houses contains human waste and other kitchen wastes. If untreated and allowed to enter into a water body, the organic content of water would increase resulting in eutrophication and growth of other microorganisms. Also the foul smell and colour of water is spoilt.
Bathing animals can release wastes like nitrogenous wastes, infectious or disease causing organisms into water bodies. Also the water can be polluted by defecation and other wastes of these animals.
Bathing human beings not only can pass on disease causing organisms, germs, nitrogenous waste, organic waste, but also soap lather, unused accessories in the water. All these can hamper the chemical balance of water and cause pollution.
Washing clothes basically releases detergents into water which alter its chemical balance.