Installing a Individual sewer system (septic system)

When installing an individual sewer system ( also known as a septic system) you will first need to contact your local Health Department to get a list of their regulations. They will vary from town to town and state to state.

Percolation Test:

  You will then have to do a percolation test.

You might be asking yourself what is a percolation test?

A percolation test is conducted by drilling or digging a hole (or multiple holes) in the ground, pouring water into the hole, and then observing the rate at which water percolates, or is absorbed in the soil. This test will determine the size of your leach lines.

You can get a chart from the local Health Department that will explain how to figure out the percolation rate of your test so you can determine the size for your individual sewer system.

For the percolation test you will need a piece of equipment (backhoe. excavator or an auger) something you can dig a hole with or bore a hole with if the ground where you are located is soft enough you could dig it by hand.

Where I live you need to dig two holes at the depth of your leach lines and one hole that has to go twice as deep as your leach lines to make sure you do not run into ground water or bedrock.

You can get more detailed instructions on how to do your perk test from your Health Department or you can hire an engineer or a contractor to do the test for you. Some states might require you to get a licensed professional to do the test.

You will also need a soil description of the ground where the sewer system is to be installed (research your area for a more detailed chart).

Soil chart

A percolation test can fail if it percolates to slow or in some cases too fast but this is not too common.

Septic Tank:

   When you are finished with your perk test and have the size of the system and construction permit from the Health Department you then need to dig out the hole for the septic tank.

Note: When choosing the location of the septic tank make sure it is out of the way of vehicle traffic (back yard or side of the house).

You want to make sure that you have an adequate slope from the house to the tank ( a minimum of 1/4″ per ft. ).

Individual sewer system (Septic) Tanks:

The size of the tank hole depends on the size of the tank.

You can get the dimensions of the tank from your local septic tank provider.

There are 5 different kinds of tanks for a individual sewer system.

  • Concrete. Concrete septic tanks. These durable tanks will usually last for several decades.
  • Steel. Steel septic tanks.
  • Fiberglass. Fiberglass septic tanks.
  • Plastic. Plastic septic tanks.
  • Aerobic. Aerobic septic tanks.


Once you get your tank set you want to make sure it is level. Then you are ready to backfill the tank. One thing you want to keep in mind when you backfill the tank is to compact the fill dirt at the back of the tank up to the outlet. You will also want to compact the front of the tank up to the inlet.

If this is not done the ground will settle over time causing the pipe to break or possibly get pulled out of the tank itself.

You can also backfill the section of the tank with leach rock this will prevent you from having to compact it.

On some septic tanks there there are multiple inlet’s and outlets so you can fine a tank for any satiation. (more common on concrete tanks).

   After backfilling the tank you can then run the sewer pipe from the house to the inlet of the tank. You will need to put in a clean out up next to the house (with in 12 inches) so if it plugs up a plumbing snake can be run down it towards the tank.

Cleanout from the House to the Septic Tank

Different Types of Sewer system Pipe:

There are 4 different types of pipe that can be used.

  • PVC: White or green thin-walled and schedule 40 plastic.
  • ABS: Black thin-walled and schedule 40 plastic.
  • Cast-Iron: Thick metal, often corroded.
  • Clay: Ceramic, similar material to a flower pot.

   When you are finished with the inlet pipe from the house to the tank your next step will be to run the pipe from the outlet of the tank to the leach lines. If you are having to run multiple leach line you will have to use a distribution box.

Outlet pipe and distribution box for the sewer system:

Septic Leach Lines:

   The two types of leach lines that can be put in. They can be configured in many different ways (to many to list here). The first type of leach line I will like to mention is leach rock. Where you will have to dig a 6 ft. deep x 2 ft. hole (this may differ depending on your location). Put 4 ft of leach rock in the bottom of the trench. You will then run a perforated pipe on top of the 4 ft of leach rock. After that you will need to cover the pipe with leach rock just enough to cover the pipe.

Note: If the depth of your leach line exceeds 6 ft. You will need to cover the pipe and fill your trench up to within 18 inches of finish grade with leach rock.

Before you backfill the trench you will need to put some type of construction builders paper over the top of the leach rock.

Builders Paper:

You can find the construction paper in the paint department of most hardware stores. Then you will need an inspection by the Health Department before you backfill the trench.

Sewer System Infiltrators:

   The other type of leach lines is an infiltrator style leach line. There are multiple styles of Infiltrators out there so you can find the right one for your particular application.

With the infiltrators your trench doesn’t need to be as deep as the leach rock leach lines. They are usually about 4 ft deep 3 ft wide and your trench needs to be level. You will need some kind of leveling interment. A grade laser or a grade leveling instrument is required to get the ground level .

photo of installed infiltrators

The infiltrators lock together to create a void under the ground for the sewer water to soak into the ground.

The reason for having 2 ft of backfill over the leach lines ( leach rock or infiltrators) is for evaporation.

  After your leach lines are installed and inspected you will then backfill the system.

  Note: you don’t want to plant, plants that have a big root system ( trees or shrubs) to close to the sewer system . The roots will follow the water into your lines and your leach system and plug them up.

sewer pipe plugged with roots
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