What is Included in a Septic Inspection?

guide to septic inspections

The septic inspection is the most challenging and physically demanding of all real estate inspections–it’s no wonder that professionals in our industry joke that it’s a ‘crappy’ job.  A good inspector should have a sharp eye, a strong back, and a robust stomach.  Conventional gravity-fed septic systems are not too complex and the inspection itself can be straightforward, as we discuss in further detail below, but gaining access to the tank and its components is the most difficult part of the job.

Why Should I have a septic system inspected?

Septic systems can fail catastrophically and in some cases, raw sewage can back up into the home.  Owners and tenants sometimes have to relocate for days or even weeks while the system is being repaired.  Raw sewage is not only a sanitary issue but can cause lasting odors, stains, water damage, and health concerns.

What are the Signs of a Failing Septic Tank?

Septic systems often fail without warning but some signs of a failing system are:

  • Ponding, standing water or saturated areas above the tank or drain field
  • Sewage smells near the septic tank or drain field
  • Sewage backing up into the home
  • Slow draining plumbing fixtures
  • Sewage odors in the home

What if the Septic Operations Permit can not be found?

A copy of the Septic Operations Permit can be requested at the county environmental health department — It is common for homes in our area (even newer ones) to have missing septic permits.  When permits are found they are helpful, but they only provide a hand-drawn diagram that can be misleading or just wrong.  Septic systems are designed based on the number of bedrooms in a house (not bathrooms) which is why the listed number of bedrooms of a house should always be referenced with the number of bedrooms that the septic system was designed for.  Western North Carolina County information can be found here.

How are Septic Tanks Located?

Most tanks haven’t been pumped in ten years or more let alone the recommended 3-5 years (some tanks haven’t seen the light of day in decades).  Over time tanks and drain fields can get buried under decks, patios, additions, outbuildings, fill/garbage/etc. or they become overgrown with shrubs and trees.  The search for the tank typically begins at the downhill side of the home to look for clues and to start probing until something flat and hard is found.  When this fails, the inspector may look for a clean-out that provides access to the camera scope.  Some camera scopes have a sonde or transmitter that allows them to be located underground.  Clean-outs are usually found in the basement, crawlspace, or outside.  When no clean-outs are found the inspector may use a flushable transmitter (about the size of a small egg) down the main waste line until it finds its way to the tank (hopefully)- the inspector then uses their locator to track it down—as you can imagine, some transmitters are never found again (money flushed down the drain).

septic inspection,septic inspection cost,septic inspection report
This is a flushable transmitter which can be flushed down the toilet to help locate a septic tank

septic inspection,septic inspection cost,septic inspection report
This is a locator that is used, in septic inspections, to locate a flushable transmitter (or other sonde transmitter) to locate septic tanks . It can also be used to determine the approximate depth of a tank.

How are Septic Tanks accessed?

After locating the corners of the tank (using a metal probe) the inspector digs over where they assume the lids might be.  Most modern tanks have two compartments—each with its own lid.  Typically, the inspectors dig 2 holes for the tank and sometimes a third for the ‘d-box’ or distribution box.  The inspector may run into rubble and roots which make the digging difficult.  Most tanks are between 1.5’ and 3’ underground– an excavator is typically needed when tanks are below 3′.   It is not uncommon to find tanks found 8’ deep in the ground or more that have been covered during re-grading projects!  The digging part of the job can take hours- sometimes in the rain, snow, or the hot sun.

How Are Septic Tank Lids Opened?

Most septic tank lids are made of thick concrete and are not easily opened.  Special tools and techniques are needed to tease them open.  Many lids are already cracked or damaged when the inspectors arrive.  Many inspectors carry standard-sized lids in the truck for replacement so they can continue with the inspection and prevent hazards to the occupants.  Some older tanks have oversized concrete lids known in our industry affectionately as ‘coffin lids’—they can be as large as 3’x5’ (over 100 pounds) and may require the use of a hoist or other special equipment to hold them open.  Most of the time the only thing that escapes from the opened lid is the sweet smell of victory (sewage gases) but occasionally raw sewage comes flooding out because the system is backing up– never a pleasant outcome. 

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There should always be a space between the effluent and the top of the tank. If the effluent level is above the outlet pipe that could indicate that the drain field is failing and backing up.

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The inlet pipe is 2″ higher than the outlet pipe. The effluent level should be level with the outlet pipe and 2″ below the inlet pipe (as in the picture)

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A typical 20″ x 20″ lid for septic tanks. Modern septic tanks will have two compartments – each compartment should have its own lid. The tank should be level and not buried more than 2.5′. Tanks should not be covered by hard surfaces (like driveways, patios, etc.) or by trees, shrubs, additions, etc.
schematic of a septic tank 2 creative commons image from wikipedia
A diagram of a typical 2 compartment tank with a baffle wall in the middle to help prevent the passage of ‘sinkers’ and ‘floaters’ (scum and sludge) into the second compartment. The outlet T is designed to prevent the floaters from entering and clogging the drain field. (Inlet T’s are not commonly found in our area)

How are Septic Tanks Inspected?

Once the inspector has exposed all the components they can perform the actual inspection.  Most septic systems are simple in concept and the design has not varied much in decades.  The main plumbing line, or sewer lateral, connects the house to the tank—the system is gravity fed so everything must slope gently downhill.  In a 2 compartment tank, the first compartment is designed to ferment the bulk of the ‘solids’ and the second compartment breaks down smaller solids into a clear liquid. The baffle wall, sanitary tees, and filter are designed to keep solids from clogging the drain field (earlier tanks do not have these). The drain field disperses the clear effluent to soil organisms near the surface for the final phase of fermentation. Sometimes when home sites do not ‘perc’ well, or accept effluent well, more complex systems are installed. In some cases, Septic Lift stations are needed that pump waste to other locations off-site where the soil is more accommodating.  Some systems look like what you might see under the hood of a diesel Mercedes Benz—manifolds, timers, valves, control boxes, sensors/alarms, etc… these are designed to simulate the fermentation process that would ideally take place in a conventional drain field.

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For a conventional gravity-fed system the inspector will verify that the inlet, outlet, sanitary tee, tank, and baffle wall are intact and functioning properly and take pictures/video.  The inspector may take a core sample from each compartment to verify they are fermenting properly.  The inspectors will verify that effluent is entering and leaving the tank and check the grading and clearances from the home, well, property line, and water sources.

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Diagram of a typical gravity septic system

Scum, or ‘floaters’, are floating solids visible from above.  Sludge or ‘sinkers’ are solids at the bottom of the tank.  When the scum and the sludge equal 30% or more of the tank, the system is overdue for pumping.

After the inspection, the inspector buries the lids and carefully replaces the sod over the dig site.  Some inspectors may cover the disturbed area with wheat straw and/or re-seed to help the grass recover.  Many inspectors will provide estimates for repair work. 

What are Common Problems with Septic Tanks?

The most common issues with septic tanks are:

  • Problems with the Outlet Tee
    • Typically an easy fix and not expensive
    • The purpose of the Outlet Tee is to prevent solids from entering and clogging the drain field
    • Deteriorated masonry tees are common with older tanks.  Newer outlet tees are made of PVC and typically do not deteriorate
    • Missing outlet tees
    • Missing or clogged effluent filter 
  • Problems with the drain field
    • Often complex and potentially expensive repairs
    • Drain field systems are made of many different materials but the most common is 4″ black corrugated pipe.  This material is easily compressed (by vehicles), damaged by roots, and is also prone to settling and clogging.
    • Trees and shrub roots will commonly damage drain fields which is why drain fields should be clear of mature vegetation
    • People often drive or park over their drain field which compresses the pipes and the surrounding soil.  
    • Ponding or backing up (the most serious septic issues) are often caused by drain field issues, it is often necessary to replace the drainage system in these cases.
  • Problems with the septic tank
    • Repair costs and scopes vary
    • Septic tanks can be made of block, concrete, brick, stone, plastic, and fiberglass-reinforced plastic
    • It is common to find compressed, crushed, or damaged plastic and fiberglass-reinforced tanks due to improper installation.
    • It is common to see deterioration in older tanks made of stone, brick, and block.  Some of these masonry tanks are collapsing in on themselves.
    • Leaking tanks, or tanks with leaking seams or cracks, are very common and in most cases will be considered acceptable by the county as long as effluent or sewage is visible or ponding at the surface.
    • Inaccessible tanks under slabs, shrubs/trees, additions, or tanks buried too deep are all too common.  These tanks will not have good maintenance, inspection, and repair access.  Repairs or in some cases replacements will be necessary.
    • Sometimes tanks are installed too close to a private well system or other body of water- this can cause possible contamination  

How Do I Get My Septic System Repaired?

Start by calling a licensed septic repair company.  They will help diagnose the problem and, if necessary, will contact the county environmental health department for design and permits, etc…  In North Carolina a list of certified installers or repair companies is listed by county here.

What are Septic Tank Risers?  Do I need Tank Risers?

Risers are cylindrical 24″ wide diameter pipes that allow access to the tank.  Typically they are plastic or concrete with a securely fastened lid.  We recommend that risers are installed over tanks that are 3′ or deeper in the ground. 

How Often Should Septic Tanks Be Inspected?

The EPA recommends having a septic tank inspected every 1-3 years or during a real estate transaction.

How Often Should Septic Tanks Be Pumped?

The EPA recommends that septic tanks be pumped every 3-5 years.  In our experience, most households in our area rarely pump this frequently.    

Can a Septic Tank Be Inspected without Pumping?

Some companies in our area will inspect a tank without pumping.  Many buyers are reluctant to spend the additional money to pump the tank when they do not own the house yet– we understand this concern and sometimes much can be learned about the system without pumping the tank and occasionally tanks do not need to be pumped. 

Should the Septic Tank Always Be Pumped with an Inspection?

Pumping the tank during an inspection is a necessary maintenance item and allows for a more complete inspection.  The state of North Carolina highly recommends that the septic tank is pumped during inspection (although they do allow it to be inspected without pumping).  We always recommend pumping the tank with the inspection for the following reasons:

  • Pumping the tank will allow the inspector to see below the effluent line
    • Pumping the tank may reveal non-compostable materials (wipes, prophylactics, tampons, etc.)
    • Pumping the tank may reveal damage to the tank below the effluent line
    • Pumping the tank will allow the inspection to continue when the tank is overfull.  When the tank is discovered to be overfull (and pumping is not ordered) very little can be learned about the system except that the tank is backing up for some reason
  • It will cost more money to have the company come back out to pump it if needed but much of the cost is digging access to the tank.
  • The additional cost of pumping ($200-$400) is negligible considering the importance of pumping and fully inspecting the tank during a real estate transaction.

How Can I Care For My Septic System?

The EPA has a great resource for septic system owners that can be found here.  The EPA discourages the use of garbage disposals with septic systems.

What Should Not Go Into the Septic System?


In our experience fats/oils/grease create a solid layer of scum on top of the effluent and prevent the aerobic bacteria from breathing and breaking down the solids.  A septic system that is overburdened with fats, oils, and grease will not be able to function properly which is why they should be separated and thrown away if possible before ever going down the drain.  Greasy foods include cooking oils, butter, bacon grease, fats, cheese, wax, heavy creams, etc…)

Non-biodegradable materials

Most wipes (baby wipes, hand wipes, etc) are not flushable or biodegradable.  We have seen some tanks that were nearly half full of wipes.  A tank full of non-biodegradable material will be able to accommodate much less sewage than it was originally designed for and will eventually cause the drain field to fail and/or the system to back up or pond in the yard.  Feminine hygiene products and prophylactics are other non-biodegradable materials we often see in septic tanks.


A properly functioning septic system relies on aerobic bacteria to break down organic solids.  Harsh chemicals (bleach/ammonia, pesticides, gasoline, paints, drain/toilet bowl cleaners) will harm or kill the bacteria and make the septic system less efficient.

How long can a Septic System Last?

According to the EPA, homeowners should budge for replacement when a tank is between 25-30 years old.

Septic Inspections in Asheville and WNC

Our Company, Builder Buddy Inspections & Testing, offers Septic Inspections with Pump with our Home Inspections, Well Inspections, Pre-sale Inspections, and Commercial Inspections.  f you are located within 40 miles of Asheville call us today to set up an appointment or schedule here.  Or see our Septic Inspections service page.

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