Septic Systems and How They Work

Home inspectors who work in rural areas often inspect houses that aren’t connected to municipal sewer lines; rather, the houses use septic systems.

What Are Septic Systems?

Septic systems are underground methods of treating wastewater used where public sewer connections aren’t available. Septic systems combine technology with nature to treat household wastewater, including sewage and “grey water” from kitchen sinks, bathtub drains and laundry rooms.

Typically, a septic system consists of an underground tank and a below-surface leaching area called a “soil absorption field.” The purpose of the septic tank is to break down organic matter while separating floatable substances such as oils and solidified grease from the wastewater. The liquid in the septic tank, which is called effluent, is discharged through perforated pipes buried in the leach field, underground chambers or lined pits, which slowly release the effluent into the soil.

There are alternative systems that use gravity or mechanical pumps to remove effluent from the tank and allow it to slowly trickle through sand, gravel, peat moss, sawdust or man-made wetlands. This step removes or neutralizes disease-causing pathogens, phosphorus, nitrogen, and other dangerous contaminants. There are also systems that disinfect wastewater or let it evaporate naturally before it’s discharged into the soil. These, however, are effective only in dry or semi-arid regions.

How a Typical Septic System Works

Wastewater from all sources within a house drains into a buried watertight container, which is typically made from polyethylene, fiberglass or concrete. Most tanks hold 1,000 gallons or more, which is the minimum size for a house with a family of four. The container holds the wastewater long enough for the solids to settle at the tank’s bottom, where it becomes sludge.

The grease and oil float to the top, forming a layer of scum. The tank’s inlet and outlet pipes are fitted with baffles to slow wastewater entry. They also keep the sludge and scum within the tank and away from the drainfield. The effluent slowly seeps from the tank and into the shallow drainfield through a pipe, where viruses, nutrients, and harmful bacteria are naturally removed. It gradually filters through the soil, where the treated wastewater is ultimately discharged as groundwater and makes its way to the aquifer. If the drainfield becomes overly saturated, it can flood, causing sewage to rise to the surface or back up into drains within the house.

How to Determine if a House Has a Septic System

If you’re unsure as to whether a house is connected to a public sewer line or served by a septic system, here are a few indicators:

  • The house’s water is supplied by a well
  • There’s no water meter on the house’s water supply line
  • There’s no charge for sewer services on the water bill or property tax bill
  • Houses in the immediate area are connected to septic systems

Once you’ve concluded that there’s a septic system, you can locate it by checking the house’s as-built drawings. If the drawings aren’t available, look in the yard for lids or manhole covers. If you’re still unsure, a septic system service provider can help you find the system.

Signs of a Failed or Failing System

A foul-smelling odor around the tank or drainfield is a sign of a faulty system, but it’s not necessarily the first sign. Here are a few other indicators:

  • Wastewater backing up into the house’s drains
  • Spongy, bright green grass on the drainfield
  • Muddy soil near the system
  • Puddles of water around the system or in the home’s basement

If any of these conditions are found by the inspector, they should be noted in his or her report. They could be signs of a leak in a pipe or a crack in the tank itself, but chances are, the tank is full and overflowing. When a tank is more than one-third full, it needs to be pumped.

Home Inspections and Septic Systems

Some additional items related to septic systems inspectors need to take into consideration when conducting a home inspection include the following:

  • Review the homeowner’s log of how often and when the tank was last pumped, which is important to potential buyers.
  • Be sure the baffles are firmly connected and free from blockages.
  • Ensure the tank is large enough for the house it serves.
  • Make a note of any trees or shrubs above the tank whose roots can enter and damage the system.
  • Disclaim any part of the system you didn’t personally inspect.

Becoming a Certified Home Inspector

When you complete Inspection Certification Associate’s Home Inspection Online Training and Certification, you’ll learn how to conduct septic system inspections and much more. ICA’s Home Inspection Training is comprehensive, affordable and convenient. Using a smartphone, laptop, PC or tablet, our online training can be completed at your own pace anytime and anywhere there’s an Internet connection.

ICA’s training is all-inclusive. You’ll be certified to conduct mold and radon inspections, for which most other home inspection trainers charge extra. You’ll also receive Home Inspection Report Software and Report Form Pro 2, which will let you create reports directly from your mobile phone following the inspection. The software is a $400 value if purchased separately, but when you choose ICA for your training, it’s included in your tuition. You’ll also have free unlimited access to our online library of home inspection reference materials. When you select ICA, all this and more is included at one low price! Click here to compare ICA’s home inspector training to our competitors to see for yourself.

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