When homeowners have their septic system inspected, the professional inspector typically evaluates:
- the structural soundness of the system components — sewer pipe, septic tank, distribution box ("D-box"), and drain field; and
- how each component is performing hydraulically and environmentally.
At minimum, a septic system inspection should include:
Plumbing....more A visual inspection of the interior plumbing that is easily accessible. The inspector is looking for any visual signs of problems.
- Is a garbage disposal present?
- Are any large water volume fixtures, like a hot tub, connected?
- Is the house plumbing vented?
- Is there more than one sewer system, like a separate sewer for laundry water?
- Are there any improper connections to the sewer, like a groundwater sump pump?
- Is there a water treatment system drain connected to the sanitary sewer?
Septic Tank. ...more This requires excavating the top of the septic tank, opening the inlet and outlet ports, and written observations of the following characteristics and conditions.
- Measure tank interior dimensions (length, width, and liquid depth) to estimate operating capacity
- Inlet piping and inlet baffle condition.
- Outlet piping and outlet baffle condition,
- Estimate the amount (thickness) of floating fats, oils and grease (scum) and distance to the top of the outlet baffle
- Estimate the amount (depth) of solids at bottom of tank and distance to the bottom of the outlet baffle
- Liquid level relative to the outlet piping (liquid level at the outlet invert is normal)
- Tank structural integrity (cracking), signs of tank deterioration (corrosion or spalling of concrete). Significant concrete corrosion is often a sign of inadequate venting.
- Any signs of leakage into or out of tank.
- Condition of outlet filter (if installed) and rinsing of outlet filter, if needed
- Recommendation for tank pumping
D-box. ...more The D-box is excavated and the cover removed. The inspector makes written observations of the following conditions and characteristics:
- D-box structural integrity, noting any sign of cracking or concrete deterioration (significant concrete deterioration is often a sign of inadequate venting).
- Observation of relative outlet elevations to determine if the outlets are level with equal flow distribution to each outlet.
- Sign of solids or scum carry-over from the septic tank.
- Liquid level relative to the outlet inverts --- noting any high water marks or other signs of past liquid surcharge within the D-box. Typically, a liquid level at or near the invert level of the outlets is a sign that the drain field is operating correctly.
This picture shows a D-box in relatively good condition; some scum carry-over from septic tank; liquid level near outlet inverts; and high water mark about 1/2-inch above outlet inverts.
Drain field. ...more The inspector does not usually excavate the drain field, but notes any of the following:
- Signs of dampness, wet soils, surface ponding, vegetation type and condition, or any other indications that the drain field may be a plugged and allowing sewage to surface;
- If drain field has inspection ports, open ports and note liquid level (if any) observed in port;
- Estimate the type and size of drain field;
- If leach pits or chambers are used, excavating and opening a chamber observation port to note conditions inside the chamber, including liquid depth and rate of liquid level drop; and
- Estimate depth of the bottom of the drain field relative to the seasonal high water table.
Pump Tank. (if present) ...more Written observation of the following:
- tank interior dimensions
- tank structural integrity and condition of concrete
- general condition of pumping equipment
- testing of pump control floats and tank alarm floats
Other Components. (if present) ...more Other system components should be inspected with written observations consistent with the above procedures.
Written Report