Household- and community-level treatment systems are the methods most likely to be used in rural areas.

Household-level water treatment is appropriate when:

• A relatively small amount of water is obtained from a well or spring and is collected and transported by hand.
• The source is contaminated and simple protective measures can neither improve water quality nor stop the contamination.
• Community resources are inadequate to meet the cost of a simple community treatment system and make it difficult to develop a centralised treatment system.
• An emergency situation causes disruption of the service and contamination of the water supply so that a long-term rapid solution is needed.

Community-level water treatment is appropriate when:

• A water source serves a larger population than can be served by household level or individual treatment systems.
• A community water source is contaminated and simple protective measures can neither improve water quality nor stop the contamination.
• Community resources are adequate to cover the cost of construction, operation and maintenance of a simple community-level treatment system.

There are several different methods of small-scale water treatment that can be employed at the household and community level. Broadly speaking these can be grouped either as filtration methods, in which water passes through a porous barrier (filter) that traps tiny particles including pathogenic microorganisms and other impurities, and disinfection methods, in which contaminants are removed by the use of various chemicals or by energy from the sun.