DIY Network

How to Construct a Residential Septic System

If your home is "off the grid," you'll need this system for a building permit.

More in Plumbing

constructing a residential septic system
  • Time

    Two Days

  • Price Range

    $5,000 - $10,000

  • Difficulty



Step 1: Create the Tank and Field Layout

Septic systems incorporate a concrete holding tank in which wastewater and waste materials from sinks, bathtubs, showers and toilets are deposited. The waste collects in the tank where enzyme and bacterial action begin breaking down the waste products, converting them into a liquid. As the level of liquid rises in the tank, it eventually reaches an overflow pipe, and is then directed into a series of covered trenches known as the drain field. The earth-covered trenches contain septic medium -- absorptive material that looks similar to foam "peanuts" used as packing material. The septic medium allows the liquid to slowly disperse into the surrounding soil.

Lay out the areas for the septic tank and drain field, closely following the plans approved by the building department. Regulations determining setbacks, distances from wells and other considerations are based on health requirements and must be adhered to.

Use bright-color spray paint and marker flags to mark off each area to be excavated.

A backhoe is needed to excavate the hole for the septic system’s tank, or tanks -- some municipalities require an additional overflow tank between the main tank and the septic field.

Measure the depth of the hole for the septic tank and dig to that level. The heavy concrete tank should rest on undisturbed earth for a firm base to prevent settling.

Step 2: Install the Septic Tank

Lower the bottom half of the concrete septic tank into the hole.

With the bottom half positioned, lift the upper half of the septic tank into place. Exercise caution, as the concrete tanks are extremely heavy and can break if placed incorrectly or dropped, and serious injury can occur.

Check the tank alignment to make certain that the top and bottom sections are seated securely.

installing the septic tank

Step 3: Prepare the Drain Field Trenches

Use the backhoe to excavate the drain field trenches according to the plans.

Attach the overflow pipe that directs the liquid from the septic holding-tank into the trenches (Image 1).

Install the septic medium in the trenches (Image 2).

Lay out mesh containers filled with septic medium to form the septic field (Image 3).

Step 4: Backfill the Tank and Field

Carefully place the dirt backfill around the septic tank to avoid breaking or disconnecting the overflow pipe.

Backfill the trenches, completely covering the septic medium with dirt to the depth specified in the plans.

Learn how to increase your home's value by keeping your septic or sewage system running efficiently at HGTV's

backfill trenches to cover septic medium