Many homes in the Unites States are in rural areas and depent on the use of individual septic systems or in some cases small community cluster systems to treat sewage.  One problem with these systems, are that they are commonly installed and forgetten unless a problem arises.  The Environmental Protection Agency concluded that the difference between success and failure of these systems depend on adequately management.  A proper system can protect public health while preserving water resources, and is economically smart.

http://cfpub.epa.gov/owm/septic/index.cfm