Septic Systems Fact Sheet
Office of Wastewater Management i Decentralized Wastewater Program
This fact sheet presents data on soil-based septic systems collected by the U.S. Census Bureau for
the 2007 American Housing Survey, based on a sampling of 55,000 housing units.
Septic System Use
• In 2007, an estimated
20 percent (26.1 million) of
total U.S. housing units were
served by septic systems. This is
an increase of 1.54 million septic
systems since 1985.
• In 2007, 22 percent (1.6
million) of all housing units less
than 4 years old used septic sys-
tems.
Demographics
Total housing units served by
septic and centralized/
clustered systems
septic
systems
(20%)
Total housing units served
by septic systems
1985
1989
2001
2007
24.6
25.1
125.8
I 26.1
22 23 24 25 26 27
total housing units (millions)
• In 2007, 50 percent (13.1
million) of total housing units
with septic systems in the United
States were in rural areas, 47
percent (12.3 million) were in
suburbs, while 3 percent
(774,000) were found in central
cities.
• In 2007, 46 percent (10.1
million) of occupied housing units
with septic systems were located
in the southern region of the
United States, followed by the
midwest with 22 percent (4.8
million), the northeast region
with 19 percent (4.2 million),
and the west with 13 percent (2.9
million).
Total housing units served by
septic systems, by rural/
urban/suburban classification
central cities
3%)
Occupied housing units served
by septic systems, by U.S.
Region***
*Total housing units served by a soil-based septic system for 5 or fewer units.
**Total housing units connected to a city, county, sanitary district, neighborhood, or
subdivision sewer system serving 6 or more units (includes centralized and clustered
onsite systems). ***Based on occupied housing units served by a soil-based septic
systems (total housing units not available by region). Source: U. S. Census Bureau -
American Housing Surveys for the United States, 1985 through 2007, Tables 1A-4, 1B-
4, 1C-4, 1D-4, and 2.4.
The American Housing Survey is conducted by the U.S. Census Bureau, Housing and Household Economic Statistics Divi-
sion every two years to determine up-to-date housing statistics. Field data cover an average of 55,000 housing units. A
sample of housing units in all survey areas was selected from the decennial census. The survey goes back to the same
housing units on a regular basis, recording changes in characteristics, adding and deleting units when applicable. This
cross-sectioning of the housing inventory gives a picture of houses and households as they change over long periods of
time. Since these estimates are based on samples, they may differ from the results that would have been obtained if a
complete census had been taken under the same interviewing conditions.
Web site - www.census.aov/hhes/www/housina/ahs/ahs.html
US EPA Decentralized Wastewater Program - For more information visit www.epa.gov/owm/onsite
EPA# 832-F-08-057 Oct. 2008
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