Many religions teach that some things, often types of food, body fluids or certain animals, are impure and somehow pollute the individual who has contact with them. Usually related to such ideas and following from them is the notion that washing in water or symbolic washing will restore the individual to a state of purity. Such beliefs were prevalent in India at the time of the Buddha. Brahmanism taught that sins could be washed away by bathing in the Ganges or other sacred rivers (M.I,39). It also taught that contact with people of lower caste, with women during their menstruation, or with certain animals such as dogs or pigs, would be polluting. The Buddha rejected the notion of ritual purity and impurity as mistaken. Contact with dirt, he said, may well defile one, but this could be remedied by simply washing (M.II,151). When told that people could wash away their sins by bathing in sacred rivers, the nun Puõõikà quipped that if this were so then all the turtles, crocodiles and frogs would go to heaven (Thi.341).

Someone once mentioned to the Buddha that he was a disciple of `the brahmins who come from the west, carry water pots, wear garlands of water plants, worship fire and teach purification by water'. Part of the ritual they taught consisted of submerging oneself in water three times every evening (A.V,263). The Buddha replied that he taught an entirely different type of purification and then proceeded to explain the practice of morality and meditation (A.V,264-8).  Real pollution, the Buddha maintained, comes from negative thoughts and immoral behaviour and that this can only be `cleaned' by changing one's heart and one's actions. He called this the `inner washing' (sinàto antarena sinànena, M.I,39). He said that to live in austerity and purity is to be `washed without water' (sinànam anodakaü, S.I,43).