Abandoned or New Septic System Inspection & Test Guide InspectAPedia® -
How to inspect & test an abandoned or un-used septic system
How to inspect & test a new, un-used septic system
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Here we provide suggestions for evaluating the condition of an abandoned, un-used, or new and un-used septic tank and drainfield. Septic systems that have never been used or systems that have been un-used or even abandoned for months or years present special concerns, and the evaluation of the condition of such a system requires different steps than for a working and in-use septic tank and drainfield.
How to Evaluate the Condition of an Abandoned or Un-Used Septic System
Determining the Condition of Never-Used Septic Systems
A septic system that has never been used should not be evaluated by a loading and dye test because chances are the septic tank is empty - the loading test volume of water run into the system is unlikely to even fill the septic tank during the test interval.
If the a septic tank is not full to normal operating level, placing a test volume of water into the septic tank will not move any test water out to the drainfield - the drainfield or absorption system will remain un-tested, and its problems will remain undiscovered.
What to Inspect & Test a Septic System is New & Un-Used
In almost any location where building codes and health codes are enforced, a building permit, a septic system design, soil percolation tests, and approval of the septic system design are required by local health or building department officials.
Contact the building department and health department to ask:
Was a septic design submitted and approved?
Are there drawings, inspection, or test result documents available (obtain copies)?
Was there a final inspection to confirm that the septic system was built as proposed?
Confirm that a septic construction permit was obtained and the system was inspected and approved as built
Identify the septic contractor who installed the system;
Ask for a site tour (offer to pay the contractor for his time) at which the contractor points out (and you mark) the location of septic components (tank, distribution box, drainfield, other site drainage components that may have been installed).
Ask if the septic contractor had to make changes to the original plan. A septic contractor might encounter a buried surprise - rocks, boulders, changes in lot or building plans, that lead to last-minute changes in the septic system layout or in the location of its components.
Ask when the work was completed and whether or not all connections (tank to house, tank to D-box, D-box to drainfield) were completed.
Septic drawing: if an accurate sketch is not already provided, locate and sketch the measurements to and location of all septic system components. See Septic Tank Location. Confirm that the as-built (which may be different than the as approved design) septic system meets all of the setback requirements - distance from well, property lines, streams, etc.
Inspect the septic system site, tank, septic distribution box, septic drainfield:
A septic tank that has never been used should be empty of sewage and water. It is possible that a small amount of water has run into a septic tank during installation if the tank was set during very wet weather, but that's an abnormal circumstance. If there is significant water in the septic tank, more than an inch, the concern is that surface runoff or ground water may be leaking into (and flooding) the septic tank: look for stains at the inlet piping, baffles, covers, tank sides, that might indicate places where water is leaking into the septic tank.
Inspect the septic tank further using the criteria that we list below,
Inspect the site for evidence of settlement, un-wanted surface runoff, or other changes that might have affected the condition of the septic system such as evidence that vehicles have been driven over the drainfield. See Septic Site Inspection Procedure and see Failure Causes - Septic Drainfields.
If the distribution box has tipped, or if there is evidence that surface water is entering the distribution box, these conditions will need to be corrected.
If the septic system is reported to be new and never used, the septic tank should be empty. Inspecting the septic tank by finding and opening its service ports will yield important data such as evidence that surface or groundwater are leaking into the septic tank (and flooding the system).
If the septic system is new and never used, the distribution box should show no evidence of flooding or ground water leaking into that part of the system.
What to Inspect & Test If an Un-used Septic System is Old
If a septic system is old, perhaps of un-known age, and it is reported that the system has been un-used for a long time, special inspection and test considerations apply.
Contact the building department and/or health department to ask if there was a septic plan, inspection, approvals for the site, and if drawings are on file. Above we suggest details that might be asked.
Inspect the septic system site, septic tank, and distribution box: find the septic tank (see Septic Tank Location), have the tank opened (be careful not to fall into a tank with an unsafe cover, and never enter a septic tank).
If the septic tank is empty and clean inside it has either been pumped or has never been used. There should be no standing water or debris in the septic tank. A steel, plastic, or concrete septic tank that has never been used will have clean sides with no sewage staining.
While the septic tank is open, look for evidence of places where ground water might be leaking into the tank (DO NOT ENTER THE SEPTIC TANK) - and check the condition of the septic tank inlet and outlet baffles to be sure they are in place.
If the septic tank is not empty inspect the sewage and effluent levels. A septic tank that was in active use but has been unused for a year or even longer should still be nearly full to the point just below its outlet pipe. A septic tank that has been un-used for many years may have lower sewage and effluent level.
But if the septic tank has no effluent, just a dried crust of sewage sludge on its bottom, it is possible that the tank has been damaged and is leaky. Something is probably wrong.
A steel septic tank is at risk of having rusted through and lost its liquid volume, so unless the test volume of water is more than tank volume you won’t be testing the drainfield.
A concrete septic tank might be cracked and leaky too – but this is less common.
If the septic system's distribution box has tipped, or if there is evidence that surface water is entering the distribution box, these conditions will need to be corrected.
Inspect the septic system site for evidence conditions that suggest damage to the drainfield, un-wanted surface water, etc:
Site conditions may have changed since the original septic tank or drainfield installation, such as changes in surface runoff, subsidence, nearby construction, vehicle traffic on the drainfield, or even damage to the septic tank, distribution box, or drainfield piping. See Septic Site Inspection Procedure.
Settlement of the septic tank, tank cover, distribution box, or settlement of areas in the drainfield. Any of these may mean that septic components have become tipped or even disconnected. For example, a poor-quality installation of septic drainfield piping with uneven trench excavation, inadequate gravel, un-compacted backfill, may have led to drainfield pipes that have become tipped, disconnected, or blocked with soil. Even a new septic drainfield, just a few months old, might fail under these conditions.
Un-wanted surface runoff that directs water onto the septic tank, distribution box, or drainfield can flood the system and may significantly shorten the life of the drainfield.
Other changes that might have affected the condition of the septic system such as evidence that vehicles have been driven over the drainfield. Driving over the drainfield compacts soil that needs to breathe, and it risks crushed or broken drainfield piping or distribution boxes.
Soil test: You might want to do a soil perc test to see if the soil drains as was claimed when the septic drainfield was built.
Septic drawing: if an accurate sketch is not already provided, locate and sketch the measurements to and location of all septic system components. See Septic Tank Location. Confirm that the as-built septic system meets all of the setback requirements - distance from well, property lines, streams, etc.
Septic loading and dye test for an un-used septic system? If inspection of the septic tank shows that the tank is full or nearly full, then a septic loading and dye test has a chance of disclosing a damaged, blocked, or failed septic drainfield. We find enough septic failures with this procedure (see Dye Tests and also see Dye Amounts, Water Volume) that it's worth performing, but beware: a drainfield that has rested for a few months and that is tested during the dry season might still have a short functional life when it is restored to year round use. Septic loading and dye tests and septic tank inspections should be accompanied by an expert visual inspection of the site as well as a collection of any available historical data.
Septic maintenance history may be available from local septic tank pumping companies. If a few telephone calls can locate a septic pumper who has serviced the property be sure to ask the contractor's opinion of the condition of the septic system.
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Thanks to Rick Kie, Email: AccHomeInsp@stny.rr.com a professional home inspector in Endwell, NY, for helpful discussion of septic testing difficulties at abandoned properties. Mr. Kie can also be reached at 607-221-8724. 09/11/2008. Mr. Kie points out that if a septic system design includes a sand bed with chlorinator, septic test dye is likely to be bleached out and will be difficult to spot.
Also see these Septic System Inspection & Testing articles
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
Failure Causes - Septic Systems Basic Septic Inspection Procedures: for septic tanks, septic drainfields, cesspools, drywells, distribution piping
Failure Causes - Septic Tanks - How to Inspect Septic Tanks and evaluate the septic tank condition, baffles, sludge levels, damage, evidence of septic failure, etc.
Media Filter Septic Systems types of alternative septic systems using sand, peat, textile, foam cube or other filter media, single pass vs. recirculating media filters, how to identify them.
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
SPOTTING SEPTIC BREAKOUTS - Spotting Dyed Septic Effluent Breakout Outside - Where Septic Dye is Likely to Show Up During a Septic Dye
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
Septic Tank Capacity vs Usage in Daily Gallons of Wastewater Flow, calculating required septic tank size, calculating septic tank volume from size measurements
Pennsylvania State Fact Sheets relating to domestic wastewater treatment systems include
Pennsylvania State Wastewater Treatment Fact Sheet SW-161, Septic System Failure: Diagnosis and Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-162, The Soil Media and the Percolation Test
Pennsylvania State Wastewater Treatment Fact Sheet SW-l64, Mound Systems for Wastewater Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-165, Septic Tank-Soil Absorption Systems
Document Sources used for this web page include but are not limited to: Agricultural Fact Sheet #SW-161 "Septic Tank Pumping," by Paul D. Robillard and
Kelli S. Martin. Penn State College of Agriculture - Cooperative Extension, edited and annotated by
Dan Friedman (Thanks: to Bob Mackey for proofreading the original source material.)
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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
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If a septic system is old, perhaps of un-known age, and it is reported that the system has been un-used for a long time, special inspection and test considerations apply. 
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