Classroom presentation on how to inspect and test septic systems
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This septic system inspection and testing classroom presentation explains Onsite Wastewater Disposal / Private Septic System Inspection, Operation, Maintenance, and Repair
to Clients. It describes detailed procedures for visual inspection of septic systems, septic system testing including
loading and dye tests and other procedures, invasive
inspection methods, septic capacity evaluation, & reporting the condition of septic systems, drywells, cesspools, leachfields, galleys and other
onsite waste disposal systems and equipment.
Future trends in on site waste / wastewater disposal & legislation pertaining to septic systems and
groundwater contamination are also discussed.
Links at the end of this class presentation provide specific and detailed articles about
locating and inspecting each specific component of a septic system as well as a detailed
procedure for conducting a septic loading and dye test.
Readers of this page should see our home page, the Septic Information Website for the complete list of septic system design, installation, inspection, diagnosis, maintenance, and repair articles available online.
The author is a Massachusetts Licensed Title 5 Septic Inspector, and a licensed home inspector New York State License # 16000005303 (inception to 2008).
Other credentials are at our bio and our contact information available online.
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
Additional technical contributors & reference sources for this article are listed below.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
What is a Septic System - What is Onsite Wastewater Disposal?
Class with text and illustrations for the inspection, testing, and diagnosis of septic systems (onsite wastewater disposal systems)
provided by Daniel Friedman at
Inspection Training Associates
Inspection Expo '98, Riviera Hotel, Las Vegas NV
October 1-4, 1998 [updated and expanded through 12/04/2006]
Waste is disposed-of on the property rather than being piped to a municipal sewage treatment plant. Actually
this is speaking carelessly. More precisely, solid waste is retained in a holding (septic) tank from which it is
periodically removed for disposal at an approved dumping facility. Clarified effluent is discharged from the
tank (onsite wastewater) and is allowed to seep into the soil on the property.
Explaining septic systems to clients
"Yuck! You mean sewage stays in my yard?" I don't want that stuff on my property!
Yep. But not to worry, properly installed and
maintained, the system can be sanitary and unobtrusive. It's true however that
some maintenance is needed, particularly periodically pumping the tank. We'll talk about that in a minute. First let's look
at a very basic understanding of what's installed and how it works.
What are the Functions of a Septic System:
In a typical modern system, waste from house
plumbing, (kitchen sink, bathroom sink, shower, toilet, laundry) flows through
house waste pipes into a two-part system: a septic tank, whose job is to
retain all solid waste, and a soil absorption system whose job is to
permit clarified effluent (liquid from the tank) to seep into the soil. In the
absorption system bacteria which occur naturally in the soil digest septic
bacteria and other pathogens so that the liquid is eventually sanitary and
doesn't contaminate the private wells, ponds, or streams. There is some
bacterial action in the tank but most of it, and all of the important action
occurs in the soil absorption system.
What are the Components of a Typical Septic System (Onsite Waste Disposal System)
What is the Septic Tank and What's its Function?
The septic tank in a modern system is a water tight container, usually concrete, sometimes fiberglass. Older steel tanks were used in many areas but
might be considered a problem because of both small size and because eventually they rust out and fail. The tank is normally "full" of liquid and
waste all the time. Since the tank is normally water tight, if we run 100 gallons of water in the house, 100 gallons of water enters the tank and pushes 100 gallons of effluent out of the tank into the soil absorption system.
The job of the septic tank is to keep solid waste from flowing out into the
absorption system where it would clog the soil absorption system. Floating debris such as grease collects in the scum layer. Heavier solid waste
eventually settles to the bottom of the tank.
Some wastewater treatment occurs in the tank, up to perhaps 40% of the total treatment needed before wastewater is discharged to the environment. Treatment in the
septic tank includes mostly anaerobic bacterial action and conversion of organic nitrogen to ammonia.
Anaerobic treatment in a conventional septic tank is slow and incomplete. You can see that the "tees" or baffles to permit only liquid effluent to flow out of the
tank to the absorption field. Alternative septic system designs, and there are quite a few, include aerobic septic systems which, by
adding oxygen and air to the septic tank, increase the level of treatment there. Septic tanks require periodic cleaning to remove solids - more on that later at Pumping Septic Tanks.
Alternative septic system designs such as aerobic septic tanks use a pump to add air (oxygen) to the septic tank or other methods to increase the level of sewage treatment in the tank. But beware of just adding an air pump to a conventional septic tank not designed for that purpose: the continued agitation waste in such a tank can lead to rapid clogging failure of the drainfield. See Septic System Design for a wide variety of alternative septic system designs including aerobic and others.
More Reading about Septic System Basics and Septic Tanks
Buyer's Guide Home Buyer's Guide to Septic Systems Inspection & Testing - What to Do, Step by Step.
Retention Time in Septic Tanks Septic Tank Pumping Guide discusses retention time and "net free area" in a tank (allowing for sludge and scum layers)
Septic Tank Inspection Procedure - How to Inspect Septic Tanks and evaluate the septic tank condition, baffles, sludge levels, damage, evidence of septic failure, etc.
Septic Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location
Tank Tees & Baffles: septic tank baffles and tees, design to prevent system clogging
Above you can see sketches of two commonly-used concrete septic tanks.
What is the Septic Leach Field. What are its Components and its Function?
Clarified effluent flows from the tank into a soil absorption system,
(SAS), also commonly called a drainfield, leach field, leaching bed. The drainfield is typically made of perforated pipes buried in
gravel-filled leaching trenches or in a leaching bed. There are other types of SAS as well, and in the case of alternative or slightly more sophisticated septic systems, perhaps a raised bed or sand
bed system.
The job of the soil absorption system is to treat the effluent by removing contaminants. This happens as the effluent
soaks into the soil where bacterial action and filtration take place to convert unsanitary liquid to a sanitary condition before it flows onward deeper into
the soil or ultimately to other locations. A biological mat forms below the SAS and performs this treatment.
Here's a sketch of side and top views of a system. Notice the three "drop boxes" also called distribution
boxes which are used to connect several perforated pipes together.
Here's an idea of how effluent flows into the soil from the soil absorption system:
The job of the distribution box, or drop-box, or "d-box" is to provide equal distribution to each absorption pipe or
trench, or in some cases to allow you to adjust the flow of septic effluent unevenly among various leachfield
lines if that's needed.
Notice that in proper operation the effluent is moving down, not up to the surface.
More Reading about Septic System Drainfields or Leach Fields
Absorption Field Design size and specifications for leach fields, absorption beds, gravelless systems, seepage pits
Planting Over Septic Systems: trees, shrubs, groundcover over the septic system: what can you plant over or near septic system components without causing a problem?
Special Types of Septic Systems and Alternative Septic Designs
Older properties used systems such as cesspools,
or tanks connected to drywells or seepage pits which worked but often have more limited capacity and/or life. Special land forms may require
special systems. In areas where there is limited space, rocky soil, or other limitations, mound systems (bring in fill for rocky sites), dosing systems
(pumps to overcome elevation restrictions) , sand filter beds (alternative treatment) , and other special systems such as recirculating
sand filters and even systems that inject chlorine into effluent for discharge into waterways may be installed. We discuss special systems if we
have reason to believe that one is installed at the property being inspected. Different test procedures may be required! See Septic System Design for a wide variety of these alternative septic system designs.
More Reading about Alternative Septic System Designs - Handling Difficult or Problem Sites
Dosing Systems, Pressure - Pressure dosing, using manifold systems, rigid pipe systems, and drip irrigation systems to control movement of septic effluent to the absorption system
Drywells design specifications for drywells, seepage pits, leaching pits
Types, Causes, and Failure Criteria for Septic Systems: Defining "Failed" Onsite Wastewater Treatment or Disposal
This section lists types of failure of septic system failure by individual system component,
the common causes of each septic component failure, and provides defining "septic failure criteria".
More detailed "how to" steps instructing how to inspect specific septic components for signs of failure are
discussed at my separate online book chapter in text that compliments material here:
How Does Each Septic System Component Fail?
If you link to that book-text, please return to the class-text here using your browser's "BACK" button. Otherwise the reader may be
confused about where you are, as the text in this class section below appears later in the book text as well.
In simplest terms, there are two visible disposal failures:
Toilets or other fixtures back up into the house - but first see "Diagnosing Clogged Drains then return here using your browser's "BACK" button.
Effluent or sewage appears at the surface of the yard, or the neighbor's yard!
Septic odors may also indicate a system failure or an imminent failure. But such odors
may also be produced by defects in the plumbing vent system or other site conditions. Beware, sewer gas contains
methane and is explosive if it reaches a dangerous concentration inside a building.
Typical causes range from things that are easy and cheap to repair, to a need for complete system replacement:
Clogged pipes
Broken pipes
Damaged tank
Tipped distribution box
Clogged/broken soil absorption piping
Clogged absorption soils (grease & solids)
Saturated soil absorption area
However there can also be treatment failures.
Effluent may not back up or appear on the surface, but if insufficiently
treated effluent reaches a private well or any stream or waterway, the
environment is being contaminated -- an unacceptable condition. Historically
many people have just worried about disposal. As the quality of drinking water
deteriorates in many areas and as population grows in many previously
thinly-populated areas, proper treatment has become the real concern for
everyone's health.
For example, if there is not sufficient soil
between the bottom of the soil absorption system trenches and the local
groundwater, the local environment is being contaminated.
Other causes of onsite wastewater disposal system failure:
Driving over the absorption system, leach field, drainfield
Paving over the absorption system
Flooding the absorption system with surface or roof runoff, or rocky, poorly-drained or under-sized sites may simply lack capacity
Improper original construction , especially on rocky, poorly-drained sites (pipes settle, for example)
Tipped or flooded distribution boxes, resulting in uneven loading of soil absorption system lines
Use of septic tank or drain field additives which claim to extend system life can generate so much activity in the tank that
solids are held in suspension and forced into the soil absorption system! Do
not add any treatments, chemicals, yeast, or other treats to a septic system. In general these treatments don't work, may ruin the system, and
are illegal in many localities. There is no magic bullet to repair a bad SAS.
Rusting steel tank covers can cause death! Rusted covers can collapse. I have reports of
children and adults who have died from this hazard, as recently as December 1997. In 2000 I consulted in a fatality involving an adult falling into a cesspool.
At a building inspection I myself stepped through a hidden, rusted-through steel septic tank cover.
Falling into a septic tank, drywell, or cesspool is quickly fatal, either from being buried by falling soils and debris, or by asphyxiation. Septic gases are highly toxic and can kill in just minutes
of exposure. Even leaning over an empty (just pumped) tank has led to collapse and fatality of a septic pumper.
Concrete tank lids: can be damaged by vehicle traffic; heavy duty covers are available.
Steel tank baffles: rust out and fall off, permitting solids to enter the soil absorption system
Steel tank bottoms rust out permitting effluent to leak into soils around the tank, possibly giving a large void in tank at time of testing,
thus subverting a loading or dye test;
Leaky septic tanks: a septic tank should be water tight. If ground or surface water leak into the tank the result is often a flooded and failed drainfield; if sewage effluent leak out of the septic tank the result is the discharge of inadequately treated effluent into the soils and in the case of a very leaky septic tank, the result may also be a too-rapid loss of effluent in the septic tank resulting in too rapid build-up of solids and total system clogging and failure.
Concrete tanks can crack or sections may separate causing leaks with the same effects as just stated
Concrete tank baffles: may erode from chemicals, detergents, poor concrete mix, water flowing over top of baffles, or may be broken by improper pumping procedures
Houses clustered around a lake: often will have a marginal system as properties were crowded
together, built as part-time summer-camps, were built without code supervision, and often were built using amateur, marginal home-made systems.
Age: eventually even a well-maintained SAS will clog and have to be replaced.
List of Septic System (Onsite Waste Disposal System) Failure Criteria
Massachusetts Title 5 lists specific failure criteria and serves as
a good model for septic inspections anywhere.
Backup anywhere in the system
Discharge of effluent to the surface, stream, etc. regardless of
whether or not septic dye is observed
Static effluent level above outlet in the D-box
System has to be pumped more than 4x/year
Metal septic tanks (municipality dependent; note that in special
site conditions small metal tanks may be the "only" solution and
may be approved by local officials. An owner/buyer must be informed of the
implications of such installations.)
Soil Absorption System (or cesspool, etc) is at a depth exposing
it to the maximum groundwater level
List of Cesspool Failure Criteria (MA)
less
than 6" of freeboard
less than 1/2 day's storage
within100 ft. of a pond or dug well (surface water supply)
within50 ft. of a private well (modern sanitary well)
between50 and 100 ft from a private well if well fails bacteria test
inMA, within Zone 1 of a public well
BOH evaluation is required if within 50ft of any surface water
List of Drainfield/Soil Absorption System Failures (leach fields, drain fields, seepage pits)
Breakout of effluent observed (& I consider odors as well)
BOH evaluation in MA if within 100 ft of surface water supply
within Zone 1 of a public well
within 50ft of a private well
between 50ft and 100ft of a private well if well fails bacteria test.
SEPTIC FAILURE SPOTS - Where septic system trouble is likely to show up regardless of septic dye testing
Maintenance Needs of Septic Systems
A principal measure to avoid system failure
is periodic tank pumping. Systems can appear to "work" for a
long time without maintenance. Modern system failure theory talks about systems
that "crash." This means that a system can appear to be ok for a
long while but may actually be getting in so much trouble that by the time a
problem is noticed it's too late to do anything about it. The system crashes
and is beyond repair. When a tank is not pumped sufficiently often there is
less settling time for waste entering the tank, so small bits of floating
solids are pushed out into and begin clogging the soil absorption system, shortening
and eventually ending its life. I've found 9-year old systems which were in
total failure for this reason.
Septic Tank pumping frequency depends on these variables:
Septic Tank size or capacity
The volume of wastewater (number of occupants)
Amount of solids in wastewater (garbage disposers)
Table I at Septic Tank Pumping Guide: When, Why, How
provides details of tank size in gallons, number of occupants in the building, and tank pumping
frequency in years.
Septic tanks will not fail immediately if they are not
pumped. However, an un-maintained septic tank is no longer protecting the soil
absorption field from solids. Continued neglect may result in system failure
and even replacement of the soil absorption field. In some cases, site
limitations may make replacement of the absorption field impossible.
More Reading About How and When to Maintain the Septic System, When to Pump the Septic Tank
Biomat Formation in the Septic System Drainfield Absorption System - what leads to drain field clogging and expensive drainfield repairs
Septic System Inspection Safety & Health Concerns:
Before discussing inspecting septic systems, cesspools, septic tanks, drainfields, etc., critical
septic inspection safety issues must be reviewed. Making a mistake can result in a fatality for
the septic inspector, septic pumper, building occupants, or anyone who has the misfortune to walk over
and fall into an unsafe or collapsing system.
Do not enter septic tanks/cesspools (fatality reports)
Do not lean into septic tanks/cesspools (gas hazards, anoxia, asphyxiation)
Note and take appropriate actions regarding unsafe tank covers
Special hazards: pumping site-built cesspools, Long Island NY Fatality following Cesspool pump and collapse
Special hazards: unsafe covers, collapsing steel tanks and covers, New York near-miss falling into septic tank, potential fatality cases involving children at two sites
Septic collapse during exploratory excavation to find equipment
Note and take appropriate actions regarding site or building unsanitary conditions (sewage backups)
Do not bring sewage-contaminated clothing into your home
Tetanus inoculations needed if working in this field
Warnings which should be in writing and orally issued to
Septic and cesspool pumpers, workers, installers
Homeowners or building occupants
Rope off and prevent access immediately if you detect a collapse risk or unsafe cover. Inform all appropriate parties.
Read: Septic System Safety: Septic System, Septic Tank, & Cesspool Safety Warnings for Septic Inspectors, Septic Pumpers, and Homeowners
How to Inspect & Evaluate the Condition of Septic Systems - On Site Waste Disposal
Septic systems should be conducted in as non-intrusive
a manner as possible. Depending on the level of service being provided by the
inspector, local conditions, and client/owner requirements, the depth of
information collected and extent of testing performed will vary widely. The
steps described below give a general outline of types of investigation
possible.
Collect Historical Information about the Onsite Waste Disposal System
Collect existing information from owner, realtor,
municipality, if available: Original "as approved" or "as
built" plans showing system components, layout, type of use, design flow,
water use records, service (pumping) and repair records.
Visual Site Inspection of the Septic System:
Examine the site for possible component locations
& other clues:
On a property by a stream, pond, storm sewer, watch out for "repairs"
that extended the SAS into these locations.
Look for site problems: rocky areas, wet areas, areas taking surface or roof
runoff and prone to flooding, odors, unusual growth, green stripes marking
leach trenches, soggy sewage erupting at the surface, signs of recent
excavation.
If a well casing is visible note its location and distance from actual or
most likely septic component locations.
Notice dry as well as wet areas; if you perform a loading/dye test you'll want to
look for changes anywhere on the property.
Even if you are not performing a septic inspection or
test, if you are able to notice obvious signs of failure and fail to report them, you may be considered
not to have conducted your inspection with professional diligence in behalf of
your client.
How to Locate Septic System Components
We're talking about mostly buried stuff here.Remember that unless you actually find and open an
access cover and confirm flow from the house into it, all you're doing is identifying
typical or likely component locations in order to assist in understanding the
property and to look for signs of failure.
Septic Plans: Never assume
that the system was installed exactly according to plan. Never assume
that components are located in the most likely space unless you have hard
evidence. Never assume that a tank cover you see is for a system
still in use; it may have been abandoned.
Main waste pipe in house
indicates only the point of exit and a likely direction for septic
components; components may be anywhere, even off the property or actually
non-existent! Look for room for a tank and for room for the SAS.
Tanks: are often buried
close (10' or more) to the building as that's where there is backfill and
a place to bury this large object; but they can be quite remote.
Rectangular outline, depression,
dry or green growth may mark a concrete septic tank; Round outline
about 5' in diameter may mark a steel tank. Watch out for unsafe covers!
Recent excavations: may
mark septic components.
Tank covers, cleanout-access ports:
may be visible;
On a fairly new property
one would not expect the SAS to be located on a rocky ridge or amongst
dense mature trees where a backhoe would not have been able to pass for
excavation.
Sewage does not flow up-hill
unless there is a pump-system or siphon system installed
Basement plumbing: may
not empty into the main system - notice the level at which the main waste
line exits the building; if it's above basement fixtures and there is no
sewage pump system you should be looking for additional septic components.
Special equipment: is
available to locate pipes and tanks, using snakes and electronic sensors.
A septic contractor or plumber in your area may have these tools; even a
simple plumbing snake from the main house cleanout can indicate probable
distance to a tank.
Distances between septic system components and wells, streams, etc. are
detailed in my
Table of
Septic and Well Distances citing various authorities and distances
to streams, lakes, farm buildings, etc.
Depressions in the ground, especially near a building, may indicate the location of a septic tank; depressions in the drainfield often will mark the locations of leach bed lines, and similarly, a depression in the drainfield area in the shape of a small rectangle may indicate the location of a septic distribution box.
More Reading About How to Find Septic System Components
OUTSIDE SEPTIC INSPECTION - - Simple Visual Site Inspection Gives Key Information About Septic System Condition
Septic Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location
Guide to Performing Septic Loading & Dye Tests
Septic Loading and Dye Testing is a useful, somewhat controversial, and not
conclusive test of a system involving placing a tracer dye in a toilet,
flushing the dye into the system, and running a reasonable test volume of water
(minimum 150 gallons or 50-gallons per bedroom) into the system to look for
signs of blockage in the building, backup in the building, or breakout of
effluent (possibly dyed) anywhere on or around the property. There is no question
that this procedure is useful in that it has disclosed numerous septic failures
and has proven that preexisting wet areas did, in fact, come from the septic
system. It will NOT find every failure condition. Below I describe the
general procedure for performing a loading and dye test of an onsite waste
disposal or "septic" system.
A very detailed description of this procedure
is at Septic Loading & Dye Test Procedure Details,
a chapter of "Inspecting, Testing, & Maintaining Residential Septic Systems"
Obtain owner permission.
If a buyer has indicated that a septic test is to be performed one might
expect the owner to have given permission for a loading and dye test but
it's not the case that an owner understands ahead of time what is going to
be done. If an owner objects to running water or performing a dye
test the inspector should not proceed with the test and should inform the
client, including the implications of the situation. A realtor present at
the inspection should, by virtue of the realtor agency for the seller, be
able to confirm that the septic test is to be performed.
Do not perform loading tests on certain systems: dosing systems and recirculating
sand bed systems may require that flows into them be limited in volume and
time; some systems can be damaged by excessive flooding.
Do not permit system pumpout right before testing:
an empty tank may be 1000 gallons or more; it
will not be filled by a typical loading and dye test, therefore the SAS
will not have been loaded at all, and false conclusions may be drawn about
the condition of the system.
If pumping and tank inspection are to be performed in conjunction
with a dye test: the optimum
procedure would be to open and inspect the tank at its normal operating
condition. The static level liquid in the tank (high, normal, low) may give
evidence of a problem that will be masked when the system is flooded. Tank
pumping may then be delayed until after the loading test has had
opportunity to test the SAS. If there is obvious tank damage (missing
baffles, collapsing tank, abnormal liquid levels) the dye test should not
proceed.
Document: when and where
water was run, at what fixtures, for what length of time, at what measured
or estimated average flow rate, and at what total volume.
Confirm water flow into main waste line:
from the fixtures where it is being run. Note
piping that may suggest presence of separate drywells and do not use
fixtures draining thereto for septic system testing. Document that
drywells were not tested if you're not performing additional tests
thereon.
Monitor water supply equipment during test:
if flow declines or stops, be sure to stop the
test to avoid possible damage to a well pump.
Watch for leaks and backup at fixtures:
check each fixture before walking away leaving
water running. Ask Douglas Hansen what happens if you don't do this.
Inspect: suspected SAS area
as well as all property areas for evidence of dye or effluent breakout
before and after the test.
Check nearby streams, storm drains: for presence of dyed effluent.
Dye often appears in 10-20
minutes if there is a gross system failure; however it may not appear for
5 days in some cases.
More Reading about Septic Loading and Dye Tests - Detailed Procedures
Dye Amounts, Water Volume: how much septic dye and how much water to use to perform a septic dye test
Dye Tests: how to perform a Septic Loading and Dye Test - the complete procedure for septic loading & dye testing, a septic function test
SEPTIC FAILURE SPOTS - Where septic system trouble is likely to show up regardless of septic dye testing
SPOTTING SEPTIC BREAKOUTS - Spotting Dyed Septic Effluent Breakout Outside - Where Septic Dye is Likely to Show Up During a Septic Dye
Excavating & Pumping Septic Tanks for Further Investigation of System Condition
This task is handled by a septic pumping company or a
company working along with a septic system inspector. I schedule the pumper to
arrive several hours after starting my inspection so I can do my loading test
if one is to be performed. A detailed septic report (such as required by MA
Title 5) includes:
Description of septic tank: age, size, condition, location
Distance between bottom of scum layer and bottom of outlet tee (want 2" or more else need pump)
Distance between top of scum layer and top of outlet tee (want 2" or more else need pump)
Thickness of scum layer
Depth of sludge layer and distance from top of sludge to bottom of outlet tee (want 12" or more else need pump)
Evidence of leakage into our out of tank (abnormal liquid top level)
Evidence of effluent backup (runs back into tank
during pumpdown). Note that a backup due to a
plugged line is not a system failure; backup due to leach area (SAS) plug
is considered a system failure.
Other defects such as damaged baffles and unsafe
tank covers.
More Reading About Pumping and Inspecting Septic Tanks
Septic Sludge & Scum Levels in Septic Tanks - Measuring the Level of Accumulated Solids, Sludge and Floating Scum in Treatment Tanks
Septic Tank Inspection Procedure - How to Inspect Septic Tanks and evaluate the septic tank condition, baffles, sludge levels, damage, evidence of septic failure, etc.
Septic Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location
Septic Tank Pumping Frequency Guide for Septic Tanks: When, How, What to Watch For when pumping or cleaning septic tanks
Septic Tanks, Steel defects and inspection suggestions for steel septic tanks
Septic Tanks, Home Made defects and inspection suggestions for home made or site built septic tanks
Excavating & Inspecting Septic Distribution Boxes
Evidence of solids carryover from the tank
Leakage in or out of the D-box
Flow not moving equally into each distribution SAS line
Evidence of backup of effluent: stains showing
liquid level has been above the outlet tee - this would be considered
evidence of a system failure.
Inspecting the Soil Absorption System of an Onsite Wastewater Disposal System
The purpose of this component is to perform final treatment of effluent in a conventional
or advanced design septic system by permitting treated effluent to flow from the septic tank
(or other treatment tank) into the soil. Bacterial action and filtering there remove additional
pathogens to bring the discharged effluent to an acceptable level of sanitation, thus permitting
its discharge into the environment. "Soil absorption system" is a general term for what people call the "leach field," "leachfield,"
"drainage bed," "seepage area," "drip area" (usually in newer alternative design systems), "septic mound"
"galleys," "drain trenches" or similar terms. If you have synonyms to add to this list,
contact me and I'll add it here.
Signs of hydraulic failure
Condition of surface vegetation
Ponding in the disposal area
Encroachments into the SAS area (building a
pool, for example)
Other sources of hydraulic loading in the SAS
area (downspouts or area drainage)
More Reading about Septic System Testing
Dye Amounts, Water Volume: how much septic dye and how much water to use to perform a septic dye test
Dye Tests: how to perform a Septic Loading and Dye Test - the complete procedure for septic loading & dye testing, a septic function test
SPOTTING SEPTIC BREAKOUTS - Spotting Dyed Septic Effluent Breakout Outside - Where Septic Dye is Likely to Show Up During a Septic Dye
Recent & Future Trends in Onsite Waste Disposal Systems
Concern for Water Quality is increasing
Text under revision.
Effluent Disposal vs. Treatment
In many states including my own New York, focus has traditionally been on successful "disposal" of
effluent which has received Level-1 treatment by a septic tank. Successful onsite wastewater "disposal" means
we don't see the waste water on the surface of a property and that a dye test does not detect it being
discharged into nearby surface streams or lakes. But successful onsite wastewater treatment
means we are not contaminating the ground water. The Massachusetts Title 5 Septic Inspection standards
and procedures make this distinction but many states have not adopted such rigorous standards (as of
January 2006).
Legislation & Mandated Upgrades
Alternative and Advanced Onsite Waste Water Treatment & Disposal Systems are Available
A "conventional" septic tank and drainfield just won't work at some sites for reasons like these:
The site is too rocky for a conventional septic system or perhaps there is no soil at all.
The site is too small for a conventional septic system
The site is too wet for a conventional septic system
The site is too dry for a conventional septic system
The site is too steep for a conventional septic system
The site is too close to a lake or stream for a conventional septic system
The community or occupants cannot afford a conventional nor an expensive alternative septic system design.
There are solutions for most site problems, including septic handling and wastewater treatment systems that can
fit in a very small space and operate completely above ground. Alternative septic system designs and products
have increased significantly in number in the past 20 years as experts have experimented with media treatment
systems and alternative materials for treatment, septic tanks, and soil absorption or even evaporation systems.
Systems that use no water or only very little water, and very important, systems that re-use graywater from
a site have been designed.
We have published a large collection of articles describing a variety of alternative septic system designs and also
have collected reference sources: books, government resources, online articles.
These articles and resources for alternative septic system designs are organized and listed at
ALTERNATIVE DESIGNS.
Global Warming and Onsite Waste Disposal Issues
12/4/2006: different areas will experience quite different concerns as weather conditions, sea levels, and
soil moisture are amended by the effects of global warming in the coming century, or perhaps much sooner.
Areas of Rising Sea Level and Effects on Septic Systems: Rising sea levels will saturate soils and make conventional in-soil disposal and treatment ineffective,
raising serious health concerns for very large populations of the earth who currently live at or close to sea level
and in coastal areas.
Amended Weather Patterns Resulting in More Rain and Effects on Septic Systems:: may occur in some areas as both sea currents (Gulf Stream)
relocate and air currents (Jet Stream) relocate. Areas of increased rainfall resulting in increased soil moisture
levels will reduce effluent disposal capability of conventional septic systems in those areas and may interfere with
treatment of effluent in the biomat.
Amended Weather Patterns Resulting in Less Rainfall and Effects on Septic Systems: areas becoming very dry may
ease effluent disposal in soils up to a point. But soil pathogens necessary to form and function as the biomat
that treats septic effluent require soil moisture. Too-dry soils may interfere with successful treatment.
Septic System Design Improvements and Products
New materials and products for septic tanks permit systems to be installed where there is no soil perc, or no soil at all.
Wastewater treatment systems are available which also can significantly reduce the distance required between septic components and wells, streams, lakes, etc.
Dosing Systems, Pressure - Pressure dosing, using manifold systems, rigid pipe systems, and drip irrigation systems to control movement of septic effluent to the absorption system
Drywells design specifications for drywells, seepage pits, leaching pits
Here are links to examples of field data collection sheets used in preparation of a septic inspection report
Examples of final, written septic inspection and testing reports are available and can be provided on request
to the author.
See
our online septic system inspection course at Inspecting Onsite Waste Disposal Systems - Septic System Testing Methods & Procedures - a Classroom Presentation
Inspecting Onsite Waste Disposal Systems class, Explaining Septic System Operation to Clients; Visual Inspection, Testing, Invasive Inspection , Evaluation, Reporting; Future Trends, Legislation
OUTSIDE SEPTIC INSPECTION - - Simple Visual Site Inspection Gives Key Information About Septic System Condition
Septic Sludge & Scum Levels in Septic Tanks - Measuring the Level of Accumulated Solids, Sludge and Floating Scum in Treatment Tanks
Septic Tank Inspection Procedure - How to Inspect Septic Tanks and evaluate the septic tank condition, baffles, sludge levels, damage, evidence of septic failure, etc.
Septic Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location
InspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest.
The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems
Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.
InspectAPedia ® Home & Site Map 
Older properties used systems such as cesspools,
or tanks connected to drywells or seepage pits which worked but often have more limited capacity and/or life. Special land forms may require
special systems. In areas where there is limited space, rocky soil, or other limitations, mound systems (bring in fill for rocky sites), dosing systems
(pumps to overcome elevation restrictions) , sand filter beds (alternative treatment) , and other special systems such as recirculating
sand filters and even systems that inject chlorine into effluent for discharge into waterways may be installed. We discuss special systems if we
have reason to believe that one is installed at the property being inspected. Different test procedures may be required! See Septic System Design for a wide variety of these alternative septic system designs.
However there can also be treatment failures.
Effluent may not back up or appear on the surface, but if insufficiently
treated effluent reaches a private well or any stream or waterway, the
environment is being contaminated -- an unacceptable condition. Historically
many people have just worried about disposal. As the quality of drinking water
deteriorates in many areas and as population grows in many previously
thinly-populated areas, proper treatment has become the real concern for
everyone's health.
InspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest. 
