How To Install A Septic Tank

If you live in a rural area, installing a septic tank may be necessary to handle waste water from your home. While it’s recommended to hire a professional, in some cases a homeowner can legally install their own septic system. This article provides a step-by-step guide on how to install a septic tank properly.

Overview of the Septic Installation Process

Installing a septic system is a complex project with strict regulations. Here are the key steps involved:

  • Research permits and regulations
  • Conduct site evaluation and soil tests
  • Create a detailed design plan
  • Obtain permits
  • Layout the system and start excavating
  • Install plumbing from house to tank
  • Place and level the septic tank
  • Add gravel backfill around tank
  • Install distribution box and drain field
  • Connect interior plumbing to the tank
  • Get inspections after each stage
  • Finish grading and landscaping around the tank

Completing these steps correctly requires proper tools and skills. Trying to cut corners or ignoring regulations can lead to expensive problems down the road.

Choosing the Right Septic Tank Size

One of the first decisions is picking the septic tank size. The general rule is a minimum capacity of 1,000 gallons for up to 3 bedrooms. Add 250 gallons per additional bedroom after that. For example:

  • 2 bedrooms: 1,000 gallons
  • 3 bedrooms: 1,000 gallons
  • 4 bedrooms: 1,250 gallons
  • 5 bedrooms: 1,500 gallons

Tanks come prefabricated from suppliers in common sizes like 1,000, 1,250, and 1,500 gallons. They are made of concrete, polyethylene, or fiberglass. Concrete is the most economical option.

How to Determine Septic Tank Location

The ideal septic tank location depends on:

  • Property topography and landscape
  • Distance from wells, water bodies, and bedrock
  • Space limitations
  • Soil conditions
  • Local regulations

General guidelines include:

  • Downhill from house so waste can flow by gravity
  • At least 50 feet from wells or springs
  • At least 25 feet from property boundaries
  • At least 10 feet from foundations or basements
  • Easily accessible for future pump outs

Steps for Installing a Septic System

Once you’ve selected the size and location, follow these key steps to install the septic tank and connected components:

1. Obtain Permits and Approvals

Most areas require permits from health departments and town officials before starting any installation. Requirements vary by location, but may include:

  • Septic system permit
  • Building permit
  • Electrical permit for pumps
  • Planning board approval

Submit a detailed site plan showing all planned components and their locations.

2. Excavate Soil and Create Bed for Tank

Use a backhoe or excavator to dig a hole at least 2 feet wider and longer than the tank size. Depth depends on tank size, piping, and desired burial depth.

Add a 6-12 inch gravel base and compact it with a tamper. This creates a flat, stable bed for the tank.

3. Install Inlet and Outlet Piping

  • Dig trenches from house to tank inlet and from tank outlet to drain field.
  • Add gravel bed in trenches.
  • Lay 4-inch sewer pipes with slope of 1/8 to 1/4 inch per foot.
  • Connect to tank inlet and outlet, leaving access for inspections.

4. Lower and Level the Septic Tank

  • Use excavator or backhoe with straps to lower tank into hole.
  • Check level on all sides. Add or remove gravel as needed to level.
  • Ensure inlet and outlet pipes line up with tank fittings.

5. Add Gravel Backfill Around Tank

Shovel gravel around tank up to the inlet and outlet pipes. This supports the tank and prevents shifting. Don’t cover pipes yet.

6. Install Distribution Box and Drain Field

Per code, install a distribution box after the septic tank. Run perforated pipes from the box to lay out the drain field trenches. Add gravel, then grade.

7. Connect Plumbing

  • Install a straight pipe from the house to the inlet with water-tight fittings.
  • Attach a septic filter to outlet pipe inside the tank.
  • Add inspection ports if required.

8. Get Installation Inspected

Most areas require the health department to inspect the tank install and piping before backfilling. Get all inspections signed off.

9. Finish Grading and Landscaping

Once approved, backfill trenches and tank with soil. Mound soil over drain field. Re-grade area for proper drainage away from the tank and field.

Following these key steps carefully allows proper septic system installation by a homeowner in permitted situations. Be sure to research local regulations and get all required permits before starting. Consider hiring an experienced septic contractor if unsure about tackling a DIY install.

Tools and Materials Needed

Installing a septic system requires numerous tools and materials. Here are some of the essential items needed:


  • Backhoe or excavator
  • Shovels
  • Rakes
  • Tamper

Pipe and Tank Materials

  • Sewer pipe (4-inch diameter, PVC)
  • Drainage pipe (perforated, 4-inch PVC)
  • Straight couplings and elbows
  • Septic tank (concrete or other approved material)
  • Filter or screen for outlet
  • Distribution box
  • Inspection ports
  • Gravel or crushed stone

Measuring and Leveling

  • Level or transit line and pole
  • Measuring tape
  • String line
  • Marking paint

Safety Gear

  • Gloves
  • Eye protection
  • Hard hat
  • Steel toe boots
  • Hearing protection
  • Dust mask
  • Reflective safety vest

Getting Permits for Your Septic Installation

Permit requirements vary significantly between jurisdictions. Research the specific permits needed in your area first. Typical permits include:

Septic System Permit

Issued by the health department or environmental agency to approve the specific septic design after reviewing your application, plans, and site conditions. May require soil analysis and percolation tests.

Building Permit

Required in most areas to confirm the installation meets all building codes for your county or town. Includes electrical inspections.

Plumbing Permit

For areas that require a licensed plumber to connect interior drain pipes to the outdoor septic plumbing.

Electrical Permit

Needed if your system includes pumps, alarms, or control panels that require wiring. A licensed electrician is usually required.

Planning Board Approval

Some towns require approval by the local planning board or zoning board even for replacement systems. Check early so this doesn’t delay the process.

Key Septic System Parts and Components

While the septic tank is the most visible component, the overall system also includes:

  • Inlet and outlet piping – Transports waste from home to tank and from tank to drain field.

  • Distribution box – Splits flow evenly to multiple trenches in the drain field.

  • Drain field – Gravel trenches with perforated piping to disperse outflow.

  • Pumps or lift stations – Raises waste to height needed for gravity flow (if needed).

  • Access ports – Required to open tank for inspections and pumping.

  • Vent pipes – Releases gas buildup from the tank to prevent pressure or odor.

  • Manholes – Located over key junction points for maintenance access.

  • Control panels – Controls pumps or other electrical components.

All components must be approved for septic system use and installed properly.

Septic System Installation Costs

A professionally installed septic system averages $3,000 to $7,000 but can go much higher depending on site conditions, local rates, system size, and type of components required.

Costs to install your own basic gravity-fed septic system may include:

  • Permit fees – $200 to $800
  • Septic tank – $1,000 to $2,500
  • PVC pipes and fittings – $500 to $1,500
  • Gravel fill – $500 to $1,500
  • Rental equipment for excavation – $500 to $1,500

Complex sites with poor drainage, shallow bedrock or high groundwater can require expensive modifications that are best left to the septic pros.

Maintaining Your Septic Tank After Installation

Once installed, proper maintenance is crucial to extend the life of your septic system.

  • Inspect the tank annually and pump every 3-5 years.
  • Use an effluent filter and add bacteria through septic treatments.
  • Don’t build or pave over the drain field area.
  • Don’t plant trees or shrubs near the tank or pipes.
  • Divert roof drains and runoff away from the drain field.
  • Fix any leaky plumbing fixtures.

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