SoilFacts
20,000 copies of this public document were printed at a cost of $ 2,767 or $ 0.14 each.
© 2004 North Carolina State University
Published by
NORTH CAROLINA COOPERATIVE EXTENSION
03/ 04– 20M– BS ( Revised March 2004) AG- 439- 13
E04- 43962
solids to your tank. Garbage disposals
usually double the amount of solids
added to the tank.
Do not pour cooking greases, oils,
and fats down the drain. Grease hard-ens
in the septic tank and accumulates
until it clogs the inlet or outlet.
Grease poured down the drain with
hot water may flow through the septic
tank, but then it can clog soil pores
completely and ruin the drainfield.
Pesticides, paints, paint thinners,
solvents, disinfectants, poisons, and
other household chemicals should not
be dumped down the drain into a
septic system because they may kill
beneficial bacteria in the septic tank
and soil microorganisms that help
purify the sewage. Also, some organic
chemicals will flow untreated through
the septic tank and the soil, thus con-taminating
the underlying groundwa-ter.
If your home has a water treatment
system, such as a water softener, the
discharge pipe from the backwash
should not be connected to the waste
plumbing system or septic tank.
Are Septic- Tank Additives
Necessary?
No. These products include biologi-cally
based materials ( bacteria, en-zymes,
and yeast), inorganic
chemicals ( acids and bases), or or-ganic
chemicals ( including solvents).
Research conducted to date on three
of these types of bacterial additives
has not shown any reduction in the
rate of solids buildup nor increases in
bacterial activity in the septic tank.
Therefore, they do not seem to reduce
the need for regular pumping of the
septic tank. Some additive products
contain organic chemicals and may
even damage the drainfield or con-taminate
the groundwater and nearby
wells.
Is Special Care Needed for
the Drainfield?
Yes. The drainfield does not have an
unlimited capacity. The more water
your family uses, the greater the like-lihood
of problems with the septic
system.
Water conservation practices can help
reduce the amount of wastewater
generated in the home. Periodically
check your plumbing for leaky fau-cets
and toilets. Uncorrected leaks can
more than double the amount of water
you use. Many soils can absorb the
200 to 250 gallons of sewage usually
produced each day by a family of
four, but these soils would become
waterlogged if an extra 250 gallons
were added. For more information on
this subject, see North Carolina Coop-erative
Extension Service publications
WQWM- 75/ HE- 250, Focus on Resi-dential
Water Conservation and
WQWM- 76/ HE- 213, Water Manage-ment
Checklist for the Home. These
publications can be viewed and
printed online at www. bae. ncsu. edu/
programs/ extension/ publicat/ wqwm/
usewtr. html.
Be sure that foundation drains, roof
waters, gutter waters, and surface
waters from driveways and other
paved areas do not flow over the
septic tank or the drainfield. Careful
landscaping can help direct excess
surface waters away from the system.
Summary
The septic system is an efficient,
inexpensive, and convenient method
for treating and disposing of house-hold
wastewater. Because not all soils
are suited for conventional systems,
comprehensive soil and site investiga-tions
must be performed before you
purchase any land.
Septic systems will adequately absorb
and purify wastewater if they are
properly maintained.
Contrary to popular belief, septic
systems are not maintenance free.
Money that is saved by not paying a
monthly sewer bill should be set aside
for regular inspections and mainte-nance.
A few precautions can save
you anguish and money. Reducing
water use, avoiding grease, cleaning
the effluent filter, pumping the tank
periodically, and properly landscaping
the yard to keep surface water away
from the tank and drainfield are inex-pensive
precautions that can help
assure your system a long life. The
North Carolina Cooperative Exten-sion
publication AG- 439- 22, Septic
System Owner’s Guide, summarizes
some important day- to- day manage-ment
and periodic maintenance activi-ties
to improve your system’s
longevity. When properly located and
maintained, your system should pro-vide
years of trouble- free, low- cost
service.
Reference
Mancl, K. M. 1984. Journal of
Environmental Engineering, Vol.
110( 1): 283- 285.
Prepared by
Michael T. Hoover, Extension Soil
Science Specialist, Department of Soil
Science, North Carolina State University
Tom Konsler, Environmental Health Super-visor,
Orange County Health Department
Appreciation is extended to Mitch Woodward,
Grace Lawrence, and Deanna Osmond for their
assistance in review of this publication and to
Janet Young for graphic design, layout, and
editing.