A septic system receives, treats and disposes of unwanted wastewater and solids from a building’s plumbing system. Solids are partially broken down into sludge within a septic tank and are separated from effluent (water) and scum (fat, oil and grease). Effluent regularly exits the tank into a drainfield where it is naturally filtered by bacteria and reentered into the groundwater. Scum and sludge must be pumped periodically and should never enter the drainfield.

Baffles are septic tank components that slow wastewater entry sufficiently to ensure the distillation of solids and prevent their release (as well as the release of scum) into the drainfield. In doing so, they protect the absorptive quality of the soil and prolong the life of the septic system as a whole. They are normally made from the same material as the septic tank—either fiberglass, steel or concrete.

When Should A Septic System Be Inspected?

The septic system should be inspected once a year, including as soon as the house is put on the market for sale. This will enhance the home’s value and avoid any liability issues that might result from a malfunctioning system. It is in the interest of a prospective buyer to insist that the septic system be inspected before they purchase the home if it has not been done recently.

Since a septic system performs its essential functions underground and out of sight, it is not uncommon for a homeowner to not have any idea where the septic system is located. This is usually not an issue except for when it comes time to inspect or pump the tank! An unknown septic location may increase the length of time for an inspection/pump while the professional searches for the location of the system.

Maintenance Tips

Inspectors should know the following information so they can inform their clients about ways they can inadvertently damage their septic system:

Only bath tissue can be flushed down the toilet. Tampons, paper towels, cigarette butts, and diapers should be put in the trash. Household chemicals such as gasoline, paint, medication, antifreeze, and pesticides can damage bacteria in the septic system and should never be flushed or dumped down the sink. Detergents and bleach can enter the plumbing system in moderate amounts.

Cars should not be driven on or near the drainfield. Their weight can unknowingly damage subterranean piping.

Only grass should be planted above the septic tank and drainfield. Roots from trees and large shrubs can cause unseen damage.

No one should ever dig or build on top of the drainfield.

All water drainage from rainwater, sump pumps, or any surface water should be diverted away from the drainfield. An over-saturated drainfield can retard the water treatment process and cause plumbing fixtures to back up.

An easy way to prolong a septic system’s life and prevent a very costly replacement is to fix leaky faucets and toilets immediately. Any waste of household water should be avoided. Taking shorter showers and not using a garbage disposal are ways to limit water use.

Some Precautions:

Inspectors should not enter the septic tank to look for cracks. Tank interiors are very dirty, and entrance should be avoided. If a crack is present, it will likely be at the level of the effluent, which will have drained from the tank through the crack. A strong sign that a crack is present is an effluent level significantly below the level of the tank outlet. A tank with cracks that allow effluent to leak into the surrounding earth is essentially a cesspool and needs to be replaced.

Above-ground water indicates an overloaded septic system, if this water originates from the tank. Inspectors sometimes use a dye flushed down the toilet to confirm that the water originates from the house and not elsewhere. While this measure can be helpful, it is not an acceptable method to test septic system functionality. Flushed dye that appears in the puddle will confirm a faulty septic system; however, dye that does not appear does not ensure a working system. Dye can take days to appear and may be too diluted to see clearly.

Septic system inspection is outside the scope of general home inspection and requires special training. Laws vary by jurisdiction, and inspectors should know them well before performing this service. They should disclaim any part of the inspection of the septic system that they did not inspect.

Septic System Dangers

Septic systems are designed to handle dangerous waste and can pose serious health hazards to homeowners and inspectors. The following are a list of precautions:

  • A professional septic tank pumping service, not an inspector, should remove solid waste.
  • No one besides a licensed, equipped professional should enter a tank. Noxious fumes such as methane can cause rapid asphyxiation and death.
  • If a septic tank shows signs of weakness, tread with caution! Collapse can be fatal. Beware of tanks with rusting metal, homemade lids, or anything else that appears unstable.

In summary, septic system inspections should be performed on an annual basis to ensure proper function. The septic tank is the most expensive household fixture and its lifespan will be shortened significantly if it is not maintained.