How much does a septic system cost?
Ashburn, VA

How much does a septic system cost?

Ashburn, VA

How much does a septic system cost?

$3,500 – $8,500(Conventional septic tank system)
$4,000 – $15,000(Alternative septic system)
$7,000 – $20,000(Engineered septic system)

Get free estimates for your project or view our cost guide below:

$3,500 – $8,500 (Conventional septic tank system)

$4,000 – $15,000 (Alternative septic system)

$7,000 – $20,000 (Engineered septic system)

Get free estimates for your project or view our cost guide below:
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Tamatha Hazen
Written by
Tamatha Hazen
Edited by
Kristen Cramer
Fact-checked by
Tom Grupa

Average septic system cost

A new septic system costs $3,500 to $8,500 installed for a conventional septic tank. The cost to install a septic system depends on the type, home size, and tank material. Septic tank prices are $1,000 to $1,500 for an average 1,000-gallon tank. An alternative septic system costs $4,000 to $15,000 installed.

Septic tank cost by system type - Chart
Septic tank cost by system type - Chart
Septic tank cost by system type
System type Average installed cost
Conventional / anaerobic septic tank system $3,500 – $8,500
Alternative septic systems $4,000 – $15,000
Engineered septic systems $7,000 – $20,000

Cost data is from research and project costs reported by HomeGuide members.

Stainless steel septic system being installed on residential property
Stainless steel septic system being installed on residential property

Conventional / anaerobic septic tank systems

Conventional septic tank systems cost $3,500 to $8,500 installed and are the type most people are familiar with. Conventional systems are primarily gravity fed and use anaerobic bacteria to break down solid waste. The systems include a pipe from your house to the tank and then to the drain field.

Conventional septic tank system installation costs
Factor Average cost
Septic tank (1,000 gal) $1,000 – $1,500
Distribution box $500 – $1,000
Labor for site prep / installation $1,000 – $4,500
Engineering, permits, and inspections $1,000 – $1,500
Total replacement cost $3,500 – $8,500

  • A septic tank is a large, underground container that treats wastewater from homes that are not connected to a municipal sewer system.

  • The septic tank collects the waste, then gravity separates the waste into scum, sludge, and effluent. Bacteria in the tank breaks down the solid waste on the bottom, while the effluent liquids travel out of the tank into the distribution box and are dispersed into the drain field.

Concrete septic tank being installed on ranch house property
Concrete septic tank being installed on ranch house property

Alternative septic systems

Alternative septic systems range widely in price from $4,000 to $15,000. These systems are designed to deal with situations where there is limited space or a drain field is not a viable option. A large home with lots of bedrooms on a small plot of land would require an alternative septic system.

Alternative septic system costs
System type Average cost installed Details
Chambered system $4,000 – $11,000
  • Uses a series of buried plastic chambers to treat wastewater
  • A good option for areas with high groundwater tables or limited space
Constructed wetland system $7,000 – $14,000
  • The septic tank is located in a wetland area and surrounded by plants that absorb nutrients in the wastewater and help filter out the solids.
Drip distribution system $6,500 – $15,000
  • Uses a series of drip emitters to distribute the treated wastewater from the septic tank to the leach field to ensure even distribution
Evapotranspiration system $10,000 – $15,000
  • The base of the drainfield is lined with a watertight material.
  • After the effluent enters the drainfield, it evaporates into the air, never reaching the groundwater.
  • Useful in arid climates with adequate heat and sunlight

Engineered septic systems

Engineered systems are the most complex and expensive to install, costing $7,000 to $20,000. Similar to conventional systems, the engineered systems collect and separate waste in a tank but use pumps to move the liquid waste into the leach field for distribution to the ground.

Engineered septic system costs
System type Average installed cost Details
Aerobic treatment unit (ATU) $10,000 – $20,000
  • Adds oxygen to the wastewater to break down solids more quickly and efficiently
  • Sometimes requires disinfection using chlorine or UV treatment before the wastewater enters the drainfield
  • Must be inspected annually at a minimum
Mound septic system $10,000 – $20,000
  • Drainfield bed that is raised above the natural soil surface with a specific sand fill material
  • Useful when there's only 1 to 2 feet of native soil
Recirculating sand filter system $7,000 – $15,000
  • PVC-lined or concrete box filled with a specific sand fill material
  • A small network of pipes is placed in a gravel-filled or no-gravel chamber bed on top of the sand.
  • Suitable when there's only 1.5 feet of native soil under the drainfield

Get free estimates from septic tank system installers near you.

Septic tank installation cost factors

The type of septic system you need is just one of many factors that come into play when estimating the cost of a septic tank installation. Other factors include your household size, tank material, soil conditions, installation labor, site prep, and permitting costs.

Truck with crane delivering new septic tank
Truck with crane delivering new septic tank

Household size

The size of a septic tank is typically based on the number of bedrooms, not bathrooms, in the home. This is because a capacity of 2 people per bedroom is a good indicator of the amount of wastewater that will be produced in the home.

Septic tank prices by gallon size
Size (gallons) Average tank cost* Average home size
750 $700 – $1,200 1 – 2 bedroom
1,000 $1,000 – $1,500 3 bedroom
1,250 $1,200 – $1,800 4 bedrooms
1,500 $1,500 – $2,500 5 bedrooms
1,750 $2,000 – $3,000 6+ bedrooms

*Not including installation labor.

Tank material

Septic tanks are buried underground and collect and treat sewage by bacterial decomposition. There are 3 different materials used for septic tanks: concrete, plastic, and fiberglass. Steel tanks are no longer installed due to their high price and low durability.

Septic tank cost by material
Material Average cost* Pros Cons
Concrete $1,000 – $3,000
  • Most common septic tank material
  • Lasts for decades
  • Heavy weight tanks will not float if the water table is near the tank level.
  • Strong enough to avoid damage by heavy machines
  • Rustproof
  • Costly compared to other materials
  • Hard to repair when damaged
  • Requires heavy equipment to transport and install
  • Prone to cracking and seepage of effluent
Plastic (Polyethylene) $700 – $2,500
  • Economical
  • Easy to handle and install
  • Lightweight
  • Rustproof
  • Resist cracking and chemicals
  • The tank is lightweight and may float upwards when the water table is near the tank level.
  • Heavy weights over the tank will change its shape and could lead to explosion.
Fiberglass (fiber-reinforced plastics) $1,400 – $2,000
  • Cheaper than concrete and steel
  • Stronger than plastic
  • High durability
  • Rustproof
  • Watertight
  • Cannot resist buoyant forces and will float or shift when near the water table

*Not including installation labor.

Concrete septic tank system installation on rural property
Concrete septic tank system installation on rural property

Soil conditions

Soil conditions also influence the recommended system size and cost. The ideal soil is loamy soil with a good balance of sand and clay that allows wastewater to drain properly. Soil depth is also important, since shallow soils may not have enough time to treat the wastewater before it reaches the groundwater.


Installation labor averages $1,500 to $4,000, or nearly 50% of the total cost of installing a septic system. Many factors influence labor costs including:

  • System size – The larger the system, the more difficult and expensive the labor.

  • System type – Some system types are also more labor-intensive, including mound systems, aerobic systems, and pressure distribution systems which require more labor to install the pumps and piping.

  • Soil conditions – Some soil types, like heavy clay, are more difficult to work with and increase the labor costs for site prep.

  • Location – Septic systems are typically installed in remote areas. Labor costs often increase for those areas to cover the added transportation costs for heavy equipment.

Site prep

Site prep and labor costs overlap since site prep is the most labor-intensive part of the installation process. The site prep required depends on the type and size of septic system you need and whether you are installing a new drain or leach field, which greatly increases the costs.

Common site prep costs include:

Excavator digging and placing a concrete septic tank system install
Excavator digging and placing a concrete septic tank system install

Permits, inspections, and testing

When installing a new or replacement septic tank system, expect to spend $1,000 to $2,000 on average for permits, inspections, and necessary testing. Requirements vary by location.

  • Building permits cost $250 to $450 for the septic tank.

  • Drain field permits cost $250 to $650 for new installations and replacements.

  • Abandonment permits cost $100 to $250 for each leach field abandonment.

  • A soil test costs $250 to $700 to measure water absorption rate., while a deep hole percolation test by a qualified engineer costs up to $2,000.

Excavator installing new septic tank for residential home
Excavator installing new septic tank for residential home

Maintenance costs

Septic system maintenance costs $150 to $1,000 per year for an annual inspection and other maintenance services as needed, including pumping, filter cleaning, hydro jet cleaning, and adding tank additives.

Septic system maintenance costs
Service Average cost Details
Septic tank inspection cost $150 – $450 Inspections as part of routine maintenance determine the condition of the tank and pipes and when the tank needs pumping.
Septic pumping costs $300 – $700 Prices depend on the tank size and condition, with larger and older tanks taking longer and costing more.
Septic filter cleaning $100 – $400 This service improves the efficiency of the septic system and may be included with pumping service.
Septic tank additives (Pro) $400 – $600 Additives are rarely needed in a well-maintained septic system but are added by a professional to an unhealthy tank to re-establish a healthy bacterial balance.
Septic tank additives (DIY) $50 – $200 While readily available, these products are best used by professionals since the additives can corrode the tank, harm the bacterial balance, and contaminate groundwater.

Repair costs

Septic tank repairs cost $600 to $3,000 on average, depending on the extent of the damage. Septic systems undergo a lot of use, especially in large households. The buried tank and pipes should be inspected regularly and repaired promptly to avoid costly sewage overflows and other damage.

If the pipe leading from the home to the tank is damaged, septic line repair costs $50 to $250 per linear foot.

Mobile home septic tank costs

Mobile home septic tank systems cost $3,000 to $5,000 installed on average, which is similar to the cost for a smaller home. Choosing the location of the septic tank is more critical for a mobile home. Avoid placing the septic system where it could be driven over, which can compromise the tank integrity.

Septic tank system FAQs

How does a septic tank system work?

A traditional septic tank system works by allowing solids to settle to the bottom of a tank, where they are broken down by bacteria. The remaining liquid, called effluent, is then discharged into a drain field where it is further treated by the soil.

How a septic tank system works
How a septic tank system works

How many years does a septic tank last?

A concrete septic tank can last for 20 to 30 years with proper maintenance. However, the lifespan of a septic tank can vary depending on the quality of the tank, the soil conditions, and the usage. A septic tank used by one person will last longer than one used by a large family.

How can you tell when you need a new septic tank system?

Look for these signs your septic tank needs repair or replacement:

  • Sewage puddled in the yard over the tank or drain field

  • Sewage odors in the yard

  • A sunken area in the yard over the tank

  • Gurgling noises when flushing the toilet

  • Sewage backups in the home

  • Slow drains in the sinks and showers

How often should I pump my septic tank?

Get free estimates from septic tank system installers near you.

Have your septic tank pumped every 3 to 5 years, depending on the tank size, number of people in your household, and your water usage.

Getting estimates from septic tank installers

If you're considering a new septic system, follow these recommendations to find a septic tank installer near you:

  • Get estimates from several licensed septic companies with 5+ years of experience.

  • Select from septic companies that are members of the National Onsite Wastewater Recycling Association (NOWRA).

  • Compare recent company reviews on HomeGuide and Google.

  • Request everything in writing, including a detailed estimate, contract, and warranty information before work commences.

  • Confirm the company acquires the right permits and follows all local municipality laws and building codes.

Questions to ask septic system installers

Here are some questions to ask when trying to narrow down the list of septic tank installers near you:

  • Are you licensed, bonded, and insured for septic work?

  • Are you a current NOWRA member?

  • How many years of septic system installation experience do you have?

  • What is included in your estimate?

  • What type and size of tank do you recommend for my household?

  • How often should I have the tank pumped?