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)
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.
|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.
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.
|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.
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.
|System type||Average cost installed||Details|
|Chambered system||$4,000 – $11,000||
|Constructed wetland system||$7,000 – $14,000||
|Drip distribution system||$6,500 – $15,000||
|Evapotranspiration system||$10,000 – $15,000||
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.
|System type||Average installed cost||Details|
|Aerobic treatment unit (ATU)||$10,000 – $20,000||
|Mound septic system||$10,000 – $20,000||
|Recirculating sand filter system||$7,000 – $15,000||
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.
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.
|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.
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.
|Concrete||$1,000 – $3,000||
|Plastic (Polyethylene)||$700 – $2,500||
|Fiberglass (fiber-reinforced plastics)||$1,400 – $2,000||
*Not including installation labor.
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 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:
Excavation costs $100 to $300 per hour for an excavator & operator.
Land leveling costs $500 to $5,000, depending on the yard size.
Leach field repair costs $1,000 to $5,000, while full replacement costs $3,000 to $15,000.
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.
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 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.|
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 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?
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?