What makes a septic system fail an inspection?

The short answer

A system fails an inspection in one of two ways. Either it has already failed by the state's own test, with sewage where it should not be, or the inspector finds a problem that will get it there: solids escaping the tank, a damaged part, a field that cannot take water, or a system too small for the house. The report should tell you which kind of problem you have, because a worn part and a dead drainfield lead to very different bills.

What Virginia counts as a failed system

Virginia's sewage regulations set the line. Under 12VAC5-610-350, "the presence of raw or partially treated sewage on the ground's surface or in adjacent ditches or waterways or exposure to insects, animals or humans is prima facie evidence of such system failure".^[1] Polluted groundwater, or sewage backing up into plumbing fixtures, may also indicate failure,^[1] but the regulation does not list those as prima facie evidence. The regulation sets this test for requiring a malfunctioning system to be corrected, and it deems sewage on the surface, in ditches or waterways, or exposed in that way a violation of the regulations.^[1] A backup still deserves a prompt call, and a good report says which findings, if any, meet that test.

Problems found in the tank

Overdue pumping. Overdue pumping is one of the most common reasons septic systems fail: solids build up until they fill the tank.^[2] By the EPA's rule of thumb, the tank "should be pumped if the bottom of the scum layer is within six inches of the bottom of the outlet, if the top of the sludge layer is within 12 inches of the outlet, or if more than 25 percent of the liquid depth is sludge and scum".^[3] A full tank alone is a maintenance item. Solids found past the outlet are a more serious finding.

Broken baffles. Baffles can degrade, more often in concrete tanks, and when the outlet baffle goes, solids can enter the drainfield and clog the soil in the trenches.^[2]

Leaks and cracks. Service providers check the tank for leaks and look at the scum and sludge layers.^[3] A tank that loses water through a crack, or lets groundwater in, is noted.

Roots. Tree and shrub roots grow toward the water and nutrients a system supplies, and they can get into and damage the drainlines, the distribution box or the tank itself.^[2]

Problems found in the drainfield

The drainfield is where most expensive findings come from. Warning signs include standing water above the drainfield, especially if it is discolored and smells, an unpleasant smell on its own, and greener grass over the lines.^[2] Green stripes are not proof on their own, since drought and low fertility conditions can cause a similar effect.^[2]

A loading test, "placing a set volume of water into the system to look for evidence of a blockage of failure",^[4] can expose a field that only looks fine because the house has been empty. Water that backs up in the tank or distribution box during the test usually points to a blockage or a field that is no longer absorbing.

Other common findings are driveways, sheds or gardens over the field, and gutters or sump pumps draining onto it. Virginia Cooperative Extension lists building or planting on the drainfield and long spells of very heavy rain that leave water standing over it^[2] among the causes of failure.

Problems found in the paperwork

Too small for the house. A system too small for the number of people in the house overloads the drainfield with water, which can badly limit how well the soil drains.^[2] Residential systems are designed on a peak flow of 150 gallons per day per bedroom.^[4] A three-bedroom permit on a house now marketed with five bedrooms is a finding even if nothing is wet yet.

Missed maintenance on an alternative system. Under Virginia rules, an alternative system must be inspected by a licensed operator at least once a year.^[5] Gaps in the operator's log, an alarm that does not work, or one that has been silenced are all flagged. If an alternative system's alarm goes off, VDH says to contact your service provider right away.^[5]

Open enforcement. The health department file may show any outstanding enforcement action, such as a Notice of Violation requiring the owner to repair a failing system.^[4]

Maintenance or repair: what happens next

Not every failed item means a new system. A licensed service provider can make simple improvements, as long as they fit VDH's definition of maintenance.^[4] Unless a local ordinance provides otherwise, Virginia's licensing rules define maintenance as adjustments to equipment and controls, or in-kind replacement of worn parts that need no construction permit, such as pumps, filters, conveyance lines and distribution boxes.^[6] Whatever a local ordinance says, maintenance does not include replacing tanks, drainfield piping or subsurface drainfields, or work that needs a construction permit and a licensed onsite sewage system installer.^[6] Your locality's rules can narrow what counts, so ask the local health department.

For bigger repairs, the owner needs a repair designed by a licensed designer and a construction permit from the local health department before the work is done.^[4] That designer is generally a private onsite soil evaluator, sometimes working with an engineer, who evaluates the site and soils and designs the repair.^[2] Our guides to the septic repair permit and drain field repair walk through that process, and why a septic system backs up into the house covers the most common symptom.

When to call a licensed pro

Call a licensed septic professional when you see sewage on the ground or smell it over the field, when drains back up, when an alternative system's alarm sounds, or before buying a house with a septic system. Virginia requires an onsite sewage system operator licence from DPOR, in the right class, for anyone who operates or maintains a conventional or alternative septic system.^[7] If the finding needs a repair design, hire a licensed onsite soil evaluator, who may work with an engineer. An onsite soil evaluator needs a licence from the state board to do that work.^[8]

For what a full inspection covers, see what a septic inspection includes, or browse more inspection answers and septic inspection services.

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