Locating the Septic Tank and Drainfield

A BEGINNER’S GUIDE Finding a septic system can be challenging. They can be

TO SEPTIC SYSTEMS the soil may appear just like the surrounding soil, making
the system difficult to locate. In dry weather, the grass
may be drier in the shallow soil over the tank and greener
Ellen Bauske | Mussie Habteselassie | Mark Risse over the drainfield where the cleaned water is released,
but this is not always the case.
Even if you do not know where your system is located,
somebody else might. The contractor who built the house
should have provided the first owner with a map of the
tank and drainfield locations. Check the paperwork that
came with your house; it might be in there.
Many buildings and homes have on-site wastewater Your local health department would have inspected the
management systems, commonly called septic systems. installation of the system and any modifications to it. They
Because septic systems are buried, it is easy to forget may have a sketch of the system location and will provide
about them as they quietly, elegantly and efficiently it on request. Unfortunately, if the system is very old, any
maintain human and environmental health. Septic records associated with it may be incomplete or nonexistent.
systems are the norm in rural areas, but they can be Look closely at the building. If the building is on a
quite common in urban areas as well. It is important crawlspace or has an unfinished basement, look for
to know if your building is on a septic system. where the wastewater pipes come together and leave
the basement or crawlspace wall. This pipe is called the
Is Your Home or Building on a Septic System? building sewer. Often, the tank is located 10 to 20 feet
The answer to this question may not be obvious. A outside of the home directly in front of the building sewer.
building that appears to be on a sewer system may
Use re-bar or a similar metal probe to “feel” for the tank.
actually be on a septic system. It is not uncommon
Before attempting this, call 811 and have the location
for renters to have little information about the fate of of your utilities marked. This free service can prevent
their home’s wastewater. Some of the following clues or you from driving a rod through your gas or water line.
indicators will help determine if the building has a septic The tank may be several feet deep, so a hammer or mallet
system or is served by a sewer system: may be needed to tap the probe into the soil. Try to feel
• The city or municipality will charge for sewer service. Take for the tank after a rain when the metal probe will move
a close look at the water bill and determine if there is a fee through wet soil easier.
labeled “sewer” or “sewer charge.” If there is a charge for this
Begin driving the probe into the ground about 6
service, the building is most likely on a sewer system.
feet from the house directly in front of the building
• Look up and down the street and search for sewage access sewer. This should be done gently; be very careful not
ports or manholes. If a sewer system passes in front of the to puncture the building sewer. Once an obstacle is
property, the home is likely to be attached to it. Ask the
encountered, gently probe again about a foot further out
neighbors if they are on a sewer or septic system. If the
and continue until the probe goes deeper, indicating you
houses on either side of your home are on a sewer system,
then it is likely that your home is as well. have reached the end of the tank. A tank is typically 5
by 8 feet, but sizes can vary. Find both ends of the tank
• However, keep in mind that even if a sewer line runs in front using this method and mark them. Keep in mind that
of the building and the neighboring homes are on a sewer
there may be rocks, pipes and other debris that “feel” like
system, your home or building may not be. If the building
is older than the sewer system, it may still be on the original
the tank, but are not. The top of the tank is usually found
septic system. 2 to 4 feet beneath the surface of the ground. Generally,
the lid or access port is on the same level as the top of the
• Check with your local health department. This agency does
tank, but it can be located on a riser as well. Your local
final inspections to ensure that septic systems conform to
health department has a list of certified professionals who
rules and regulations. They may have a record and/or a map
can also help you locate your system.
of the system and will provide this information on request.
Once the tank is located, draw a rough sketch of its
All property owners need to know if their property has location relative to the house so it is not lost again!
an on-site wastewater treatment system. In Georgia, the Now that the tank is located, it may be easier to find the
property owner is responsible for the smooth operation drainage lines by looking for greener grass, particularly
of the septic system and any maintenance and repairs. after dry weather.
How a Septic System Works
The septic system consists of three components (Figure
1): the tank, the drain lines or discharge lines, and the
soil treatment area (sometimes called a drainfield or
leach field).
DISTRIBUTION
Tank sizes vary depending on the size of the building. SEPTIC BOX
TANK
The average home (three bedrooms, two bathrooms) BUILDING
will often have a 1,000-gallon tank. New tanks must SEWER DRAINFIELD
have two chambers, while older tanks may have only
one. The tank is often made from concrete, but other
materials are also used.
The tank works by settling and microbial digestion of
waste. As wastewater flows into the septic tank, three
layers are formed (Figure 2): a bottom sludge layer,
the top scum layer and a “clear” zone in the middle. GROUNDWATER
Heavy solids settle to the bottom, forming the sludge
layer, and grease and light solids float to the top to Figure 1. A typical septic system.
form the scum layer.
Bacteria and other microbes are responsible for
partial decomposition of the sludge. Fortunately,
many of the microbes involved are present in large
numbers in the human intestine. A new supply of
these is added to the septic tank with each flush
(no additives are needed). However, the microbes
cannot break down all the material in the sludge,
which is why septic tanks need to be pumped out
every three to seven years.
Baffles on the discharge side of the septic tank
only allow water from the middle layer to go out to
the field lines. As new water comes into the septic
Figure 2. A typical septic tank.
tank, an equal water volume is pushed out the
discharge lines and into the drainfield. There may
be a distribution box located between the tank and
drain lines, sending wastewater to several lines in
the drainfield. The water trickles out the perforated
drain lines, through a layer of gravel and into the
soil (Figure 3).
The soil is teeming with life. Plants, bacteria, fungi
and protozoa, along with larger creatures such as
mites, earthworms and insects, thrive in the soil.
All these creatures help release nutrients and other
compounds from the wastewater, using and reusing
them in the soil and cleaning the water. Minerals
and metals bind to soil particles, removing them
from the waste water. The treated water eventually
moves into ground water. Figure 3. A typical drainfield.

Figures 2 and 3 reprinted with permission from: CIDWT. 2009. Installation

2 UGA Cooperative Extension Bulletin 1421 • A Beginner’s Guide to Septic / On-Site Wastewater Management Systems
Maintaining a Septic System
Poor maintenance is the most common cause of septic system failure. Failing septic systems are expensive to repair or
replace, and the cost of repairs falls on the property owner (Figure 4). Fortunately, it is relatively easy to maintain your
septic system and avoid expensive repairs.
Have the tank inspected and pumped periodically, ideally every three to seven years. If you don’t know the last time
the tank was pumped, pump it. Previous property owners may have overlooked this essential step.
Do not drive or park over the tank or drainfield. This may damage or collapse the tank or drain lines or compact the
soil, decreasing the efficiency of the drainfield.
Do not use sinks or toilets as trashcans. Dumping cooking oil, paper towels, hygiene products, household chemicals,
paint, kitty litter, coffee grounds or cigarette butts into sinks or toilets will increase the sludge layer in the tank and, at
best, it will have to be pumped more often.
Remember, garbage disposals increase the need for routine pumping. Eggshells, bones and vegetables do not digest
well and add more sludge to the tank.
Consider the septic system in the landscape design. Tree and shrub roots can grow into the drain lines and even
the tank. Also, it is not wise to eat vegetables grown over drainfield lines (see Dorn, S. 2013. Ornamental Plantings on
Septic Drainfields. University of Georgia Cooperative Extension. C 1030).
Use water wisely. Any water that goes down a drain or toilet ends up in your septic system. Repair leaking faucets and
toilets to prevent water overload. Don’t overtax the system by using a lot of water in a short time. Keep in mind that a
saturated drainfield may not be able to absorb water from multiple loads of laundry on a rainy day.
Do not use additives. The Georgia Department of Public Health discourages the use of additives in septic systems,
and scientific studies offer little support for their use. Additives are sold as treatments, cleaners, restorers, rejuvenators
or enhancers. Biological additives, sold as starter agents or aids for routine maintenance, are made from bacteria,
yeast or enzymes. Chemical additives are sold to break up oil and grease or unplug drains. Additives do not jump
start a new or recently pumped system. They do not eliminate or reduce the need to pump out the septic tank. In fact,
chemical solvents can break solids into smaller particles that do not settle to the bottom of tank. These small particles
remain suspended in the water and move into the drainfield, potentially clogging the lines. Acids can corrode
concrete tanks and distribution boxes.
Signs a Septic System is Failing
These are signs of a failing system:
• Sinks and toilets drain slowly
• Backed-up plumbing
• Gurgling sounds coming from the plumbing
• Sewage odors in the house or yard
• Wet or mushy soil in the yard
• Standing water that is greyish in color
• Grass growing faster and greener in one particular area
of the yard
• Bacteria in well water
If any of these signs are noted, contact your
local health department. A health department
environmentalist can help identify potential Figure 4. Poor maintenance is a common cause of septic system failure. It is in
problems. The local health department also has lists your best interest to know where the system is, how it works and how to maintain it.

of state-certified contractors who can make repairs.

UGA Cooperative Extension Bulletin 1421 • A Beginner’s Guide to Septic / On-Site Wastewater Management Systems 3
 Problems with a septic system must be addressed. Failing systems release partially treated household waste into the
environment. Untreated human waste is a health risk. It can contaminate nearby wells, ground water, streams and
other sources of drinking water. It can also pollute rivers, lakes and shores. The nasty smell of a failed system can
cause property values to decline. Failed systems can delay property sales and halt building permits. In a nutshell,
failed systems can impact your family, your neighbors, your community and your environment. Yes, it can be very
costly to repair or replace a failed septic system, but a properly working and well-maintained system is vital.
Septic systems are an efficient, elegant and inexpensive way to treat and dispose of wastewater. When properly
maintained, they can protect and maintain both public and environmental health for years.

extension.uga.edu
Bulletin 1421 Reviewed March 2017
Published by the University of Georgia in cooperation with Fort Valley State University, the U.S. Department of Agriculture, and counties of the state. For more information, contact your local UGA Cooperative Extension office.
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