There are many types of onsite sewage disposal
systems in use today. One of the most common is a
septic tank, followed by a lateral drain field. Septic
systems can be installed only if the soil is permeable.
A soil scientist can evaluate the soil and determine
a permeability rate. The soil will give the sewage
effluent final treatment and disposal.
A standard septic system consists of a septic tank,
a distribution device (either a flow splitter or
a distribution box), and the drain field. Septic
tanks can be made of concrete, plastic or fiberglass.
They must be of watertight construction. Septic tanks
must have a riser that extends to the surface, allowing
the tank to be pumped periodically. Effluent filters
are recommended to be placed in the outlet sanitary
tee of the septic tank. Effluent filters are very
effective in stopping solids from leaving the tank
and clogging the drain field. A distribution device
is not needed if the lateral field is installed level.
If it is not level, a flow splitter may be necessary
to distribute the effluent equally to all laterals.
The drain field. can consist of gravel with perforated
4" pvc pipe. Recommended alternatives are gravellous
pipe or chambers.
Regular maintenance of a sewage system is the best
prevention of failure. Periodic maintenance can significantly
lengthen the life span of a system. Water conservation
and waste disposal habits are also important.
following guidelines should be followed:
- Practice water conservation. Water usage should
be monitored to prevent flooding the system. (ie:
stagger loads of laundry throughout the week instead
of doing all of the laundry on Saturday.) Water
saving fixtures in the shower and toilets can also
greatly cut down on the amount of water used. Any
water leaks must be promptly repaired.
- Do not use your sewage system as a trash can by
adding materials other than domestic sewage. Keep
chemicals (paint, thinner, pesticides, etc.) and
non-degradable items (disposable diapers, sanitary
napkins, cigarette butts, etc.) out of the septic
- Restrict the use of a garbage disposal. If a garbage
disposal is used the extra solids introduced into
the tank can increase the accumulation of sludge
by more than 50%, requiring more frequent pumping.
- Do not pour grease or oils down the sink drain. They can clog up your drain field.
- Have the solids pumped out of your septic tank
periodically. This will need to be done every 3
to 5 years depending on the size of the family
living in the home. Keep a record of pumping, maintenance
and other inspections. Keep a sketch of the system
for future reference.
- Clean the septic tank filter (if you have one)
by hosing the filter off back into the tank annually
or as needed.
- Don’t cover the absorption field with a
hard surface, such as concrete or asphalt. Grass
is the best cover for the field. Grass will not
only prevent erosion, but will help remove excess
- Keep surface waters away from the tank and drain
field. This includes downspouts from your homes
roof gutters. Also keep foundation drain and sump
pump discharge out of the system.
- Do not drive automobiles or heavy equipment on
- Do not disturb the area near the sewage system
or the set aside repair area.
Return to the Environmental Health Division Homepage or return to the Columbia/Boone County Health Department Homepage