As an essential component of septic systems, septic tanks provide onsite wastewater treatment for millions of homes. However, because they are buried underground, most homeowners never actually see their septic tank. Knowing what a septic tank looks like helps maintain these systems properly. This article provides a visual guide to septic tank components, layouts, and access points.
Septic Tank Basics
A septic tank is an underground, watertight container typically made of concrete, fiberglass, or polyethylene. Key roles of the septic tank include:
- Collecting all wastewater from the home.
- Settling out solids from the wastewater.
- Providing initial treatment of contaminants.
- Storing and slowly releasing effluent to the drain field.
Understanding what a septic tank looks like inside and out makes it easier to perform inspections, pumping, and repairs.
What a Buried Septic Tank Looks Like
For underground septic tanks, the only visible exterior components are the access covers and pipes:
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Concrete or plastic covers – Access lids over inlet, outlet, and inspection ports. About 2 ft across.
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Vent pipe – Vertical PVC pipe extending above ground to vent gases.
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Inlet pipe – 4-inch pipe carrying wastewater from home to tank.
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Outlet pipe – Smaller pipe directing effluent to the drain field.
The tanks themselves are completely buried, usually 5-25 feet from the home’s foundation. They are rectangular or cylindrical and range from 500-1500 gallons. The covers sit flush with the ground when properly installed.
What an Above-Ground Septic Tank Looks Like
Some septic systems utilize above-ground tanks made of fiberglass, plastic, or other durable materials:
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Large cylindrical shape – Above-ground tanks have rounded sides. Size depends on capacity.
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Access hatches – Removable lids on top over the inlet, outlet, and inspection ports.
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Vent pipe – Extends vertically from tank to release gases.
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Inlet/outlet pipes – Enter and exit the tank through fitted openings.
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Concrete collar – Made of concrete blocks to prevent floating.
Above-ground tanks are less common but allow for easier access and maintenance.
Inside the Septic Tank
While homeowners should not open their septic tanks, knowing what’s inside provides an understanding of how tanks work:
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Inlet tee – Pipe delivering wastewater into the tank.
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Baffles – Hold back solids from exiting the tank.
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Scum layer – Grease and fats floating at top of water.
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Clear zone – Clarified effluent zone in center.
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Sludge layer – Solids settled at bottom of tank.
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Outlet tee – Sends clarified effluent to drain field.
Bacteria help separate and digest the heavy solids into sludge and lighter scum.
Accessing the Septic Tank
Professionals utilize the access ports when pumping or servicing tanks:
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Manholes – Large, removable covers allowing pumper truck access.
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Inspection ports – Provide access to inlet and outlet tees for inspection.
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Effluent filters – Screen solids at the outlet that can be cleaned.
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Risers – Extend ports to grade for simpler access.
Homeowners should not open ports but mark locations for service visits.
Septic Tank Diagrams
Diagrams help visualize the internal septic tank layout:
Fig. 1 – Diagram of inside a typical septic tank
Fig. 2 – Diagram of overall septic system layout
Key Takeaways
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Buried septic tanks cannot be observed but access points protruding from the ground provide external clues.
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Above-ground tanks allow for direct viewing but occupy yard space.
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Inside, wastewater separates into scum, sludge, and effluent zones critical to treatment.
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Access ports permit pumping and service but should only be opened by professionals.
Knowing what a septic tank looks like, both above and below ground, helps homeowners understand these important onsite systems. Be sure to locate your tank access lids and register the tank with your local health department.