Understand Your Septic Tank & How It Works

The first step to understanding your septic system is to familiarize yourself with what you have. It is important to know that your system was designed specifically for your home taking into consideration, number of bedrooms (estimate of number of people), soil type and depth to water table or other confining layer. If you don’t already have your septic system drawing, you can contact your county permitting office to request a copy.

Septic System Basics

Septic systems can come in various shapes, sizes, configurations, and technologies. However, in their most basic form, they involve two main components:

  1. A septic tank to separate and collect solids.
  2. A soil absorption system (aka leach field) for filtering and treating wastewater prior to leaching clean water back into ground.

What Are The Main Parts Of A Septic System?

A typical septic system has four main components: a pipe from the home, a septic tank, a drainfield, and the soil. Microbes in the soil digest or remove most contaminants from wastewater before it eventually reaches groundwater.


If you’ve ever had a septic inspection, then you’ve probably heard or read about ‘baffles’, ‘inlet tees’, ‘d-boxes’ and ‘absortion areas’. A septic system is a big responsibility, and its complexity can leave some homeowners feeling overwhelmed. Understanding its parts and how they work can make maintenance easier. Here are the septic terms you should know:


The septic tank itself is a durable, watertight container that is resistant to corrosion or decay, e.g., concrete, plastic or fiberglass. 

The septic tank serves as a settling basin: heavy solid wastes (sludge) sink to the bottom of the tank where microbial action will ultimately reduce it by as much as 50% over time; and lighter solids, e.g., grease, toilet paper, and hair, rise to the surface to form a floating layer of scum. A typical septic tank will “hold” the wastewater for at least 24 hours to provide adequate time for separation and settling.

The waste held inside the septic tank separates into three layers:


    • Scum Layer: This is the top layer in your tank made of oils, fats and soaps. It is usually the first thing you’ll see floating at the top when you open the tank.
    • Liquid Layer (AKA Effluent): The middle layer is made of the remaining water after the scum and sludge have separated. The water from this layer exits into the secondary treatment to keep waste levels balanced in the tank.
    • Sludge Layer: The sludge layer contains heavier solids that sink to the bottom of the tank. This is where the decomposition process continues by means of bacteriological interaction.


These are long pipes with lids on the top of the septic tank. The risers extend to ground level allowing easy access to the septic tank for inspection and cleaning. With risers, you won’t have to dig up your septic tank every time it needs servicing. 


Device on inlet and outlet ports of septic tank. The sanitary tee pipe at the tank inlet slows the incoming rush of water to prevent disturbance to the scum layer and reduce turbulence. The sanitary tee pipe located at the tank’s outlet keeps solids, scum and grease from leaving the tank and entering the soil absorption system.


A septic tank baffle is part of the tank’s inlet and outlet on the pipe. The baffles are found inside the tank on either side of the inlet and outlet of the pipe. The function of the septic tank baffle is to help with the flow of wastewater. The baffles will dispense the water down into the bottom of the septic tank.


This filter prevents solid waste and debris from entering the secondary treatment. You can find them installed on the outlet baffle. 


(aka D-Box) – Level, watertight structure which receives septic tank effluent and distributes it in substantially equal portions to two or more lines leading to a leaching area.


Pipe used for dispersion of septic tank effluent into leaching trenches or leaching fields.

Morris Plains NJ Septic Service


Part of an on-site system: the area of ground and system of subsurface pipes or chambers into which partially treated wastewater from the septic tank is discharged for final treatment and absorption by soil. Also called Leach Field, Drainfield or Absorption Field

Septic System Replacement in Sussex,Warren & Morris County NJ

Thanks for reading our post – if you have unanswered questions about your septic tank or septic system, feel free to reach out to us.  We take pride in providing straight-forward, no BS solutions to our current and prospective clients. For over 20 years, we have been providing outstanding septic system service to homeowners and businesses across northwestern & northern New Jersey.