Although communities may lack knowledge of modern medical explanations of disease, they often have concepts of what is pure and polluting. Of the water resources available to particular households for domestic purposes, running water may be most acceptable for drinking because it is exposed to the sunlight; it is considered to be "alive" and therefore "pure", while water in shallow wells, which does not have these attributes, is deemed suitable only for washing and cooking. Communities have been observed to use the environmental resources available to them, such as bamboo, to bring fast-flowing river water to their villages in preference to more convenient well water that is unacceptable in taste, colour and smell.
Concepts of clean and dirty, pure and polluting, are well developed in the major world religions, and have a ritual and spiritual significance as well as referring to a physical state. When people are told that new sanitation facilities will make their environment "cleaner", it is their own interpretation of this concept that will be used. "Clean" may have quite different meanings to project promoters and recipients. Thus "it is essential to look into traditional categories of cleanliness and dirtiness, purity and pollution before embarking on a campaign to motivate people to accept a project in improved ... sanitation or to change their behaviour to comply with new standards of 'cleanliness'" (Simpson-Hebert, 1984).