Septic Tank System Cost Breakdown
The total cost to install a septic system will ultimately depend on three factors—the materials and labor required to install the system plus the cost to dig a leach field on your property.
Size of a New Septic Tank
The septic tank size you need will depend on the number of bedrooms your home has. This is because larger houses tend to have more sinks, toilets, bathtubs, and other wastewater sources that flow into the septic tank. As tank size increases, so do costs.
| House Size | Tank Size (Gallons) | Cost Range |
|---|---|---|
| 1 bedroom | 500 | $500 – $900 |
| 2 bedroom | 750 | $700 – $1,200 |
| 3 - 4 bedroom | 1,000 | $900 – $1,500 |
| 5 - 6 bedroom | 1,200 | $1,200 – $1,600 |
| 6 - 7 bedroom or small duplex | 1,500 | $1,500 – $2,500 |
Materials
Septic tanks are commonly made of several different materials, each with different lifespans. The septic tank material you choose will impact the price you pay.
Plastic
Plastic septic tanks cost $500 to $2,500 on average, not including installation labor costs. Plastic is durable, lightweight, and relatively inexpensive compared to other materials. It rarely cracks and cannot rust, but its lightweight nature makes it vulnerable to damage during installation.
Fiberglass
Fiberglass septic tanks cost $1,200 to $2,000, not including installation labor. Like plastic, fiberglass won’t easily crack or rust, but it’s vulnerable to damage during installation. It may also be more susceptible to structural damage because it is lightweight, especially since the tanks can shift around in the soil.
Steel
Many local building codes don’t allow steel septic tanks due to their tendency to rust or corrode underground. You’ll likely never see a new one installed, though you may see one in an existing installation.
Concrete
Concrete septic tanks cost $700 to $2,000 for the tank alone, or $2,300 to $6,500 for the tank plus installation labor. While durable for a couple of decades, they are susceptible to cracking or separation over time. You can prolong the lifespan of a concrete septic tank with regular inspections and cleaning, usually every one to three years.
Labor
Labor costs can differ by region and will depend on the size and materials of the new septic tank system. But in general, labor costs account for 50% to 70% of the total septic tank system cost. You’ll likely pay more for installation than you will for the tank alone, which is worth it when you don’t have enough room on your plate to take on yet another home project.
Make sure you discuss details with your contractor or plumber. If they don’t cover excavation costs, expect to pay another $1,200 to $4,500.
Land Survey
You’ll need to get a land survey before you can install a septic system. This makes sure that your plans fall within property lines (and saves you a legal headache lest your neighbor sues for mixing them up in your bathroom business). Expect to spend $330 to $900 for a licensed land surveyor.
Percolation Test
Before you can install a septic system, you need to have a perc test performed by a local perc test pro. This test will measure the soil type and height of each sediment layer on your property to determine the best type of septic system for you. The cost to test soil is $700 to $2,000.
Leach Field Installation
Septic tank systems consist of a septic tank and a kind of trench, commonly referred to as a leach field or drain field. This section of your septic system transports the wastewater back to the soil. Drain field installation costs $2,000 to $10,000.
Permits
Depending on the laws where you live, you may need to obtain one or more building permits or licenses to install a new septic system. Permits typically cost anywhere from $450 to $2,300, though some jurisdictions have lower fees. Check on the rules in your local area before breaking ground to avoid surprise fees later on.
Septic System Cost by Type
Each septic system type comes with its own set of pros and cons. While anaerobic systems are relatively low-maintenance, they aren’t great for small properties. Similarly, anaerobic systems can do well in small spaces but require extra work.
Anaerobic
Septic tanks can be either anaerobic (not needing oxygen) or aerobic. Anaerobic systems are more common and cost between $3,000 and $8,000 on average. They’re typically cheaper to install than aerobic systems but are less efficient and call for a larger leach field.
In an anaerobic septic system, a pipe runs from the house to the septic tank where another pipe runs from there into the leach field. Anaerobic bacteria break down solid waste before the system distributes the wastewater into the soil. These systems don’t require extra power or chemicals, making them a popular choice among homeowners.
Aerobic
Aerobic septic systems utilize oxygen pumped into the tank to activate bacteria that feed on the solid waste. These systems are more expensive than anaerobic systems at $10,000 to $20,000, but they’re more efficient and can work well for smaller properties. Unlike anaerobic systems, they do need additional power to run. To ensure everything works properly in the case of a power outage, hook it up to a power generator. Otherwise, aerobic systems can plug into your property’s main power source.
Alternative Septic System Installation Cost
Sometimes a property isn’t suitable for a traditional septic system—whether you have a high water table, high bedrock, poor soil quality, or a smaller-sized property without room for a regular drain field. In this case, you may want to look into alternative types of septic systems.
| Type of Alternative Septic System | Price Range |
|---|---|
| Mound | $10,000 – $20,000 |
| Sand filter | $7,000 – $18,000 |
| Chamber | $5,000 – $12,000 |
| Drip | $8,000 – $18,000 |
| Evapotranspiration | $10,000 – $15,000 |
| Build wetland | $5,000 – $12,000 |
Mound
Expect to spend more on a mound septic system—they cost $10,000 to $20,000 to install. They pump wastewater from the tank into a sand mound, which is built over top of the septic system area. The sand filters the water before it goes into the soil and groundwater. These systems are expensive, but they’re necessary in areas with a high water table.
Sand Filter
Sand filter septic systems use a pump to push the wastewater through a sand filter at a low pressure before it enters the soil or groundwater, effectively treating and removing nutrients. Nutrients like phosphorus and nitrogen naturally occur in waste, but they can reduce water quality and damage aquatic ecosystems when they accumulate in surface water.
They cost between $7,000 and $18,000 and can be built either above or below ground. Sand filters protect the underlying water table from not-so-clean septic wastewater (great news for the environment), and they can last decades. These systems are best for areas with high water tables or that are near bodies of water.
Chamber
Chamber septic systems are similar to conventional systems, but they use plastic chambers in the leach field rather than gravel. They cost $5,000 to $12,000 to install. Chamber septic systems are great choices for places where input volumes vary, like vacation homes.
If you do opt for this style, avoid placing it near your driveway or parking area as driving over it could cause serious (and smelly) damage.
Drip
Drip septic systems use drip tubing and a dosing system to periodically release smaller, timed doses of waste. They work well in areas with a shallow soil depth. Drip septic systems require more components than a conventional septic system, including a dosing tank and pump, and can cost anywhere from $8,000 to $18,000, depending on their size.
Evapotranspiration
Evapotranspiration septic systems cost $10,000 to $15,000 and are useful in arid climates and in areas with shallow soil. They have unique leach fields that allow effluent to evaporate from the top of an open-air tank. If you live somewhere where there’s a chance of snow or rain, just say no to an evapotranspiration septic system. The moisture could ultimately cause them to fail, and the repair process for a septic tank isn’t glamorous.
Built Wetland
As you may have already guessed, built wetland septic systems mimic the natural water treatment process seen in wetlands. Microbes, plants, and bacteria treat effluent in a wetland tank before releasing the wastewater into the soil. In turn, the waste helps the plants and microbes thrive. These sustainable systems run from $5,000 to $12,000.
Additional Costs to Consider
Consider the following additional services you may need to estimate the true cost of your septic system installation project.
Old Septic Tank Removal
If you’re replacing your septic system, your contractor will first have to remove the old system. Expect to pay a pro anywhere from $45 to $200 per hour for removal, on top of the cost of a new septic system.
Land Clearing Costs
Land clearing involves removing obstructions like trees and bushes that would otherwise get in the way of the project. Your installers may clear the land for you, or you may need to hire a separate land clearing company near you to prep your property. Either way, expect to pay $1,200 to $4,800 for this service.
Landscaping Costs
Septic tank installation involves a lot of excavation that can leave your yard looking like a barren dirt lot. After installation, you may want to hire a nearby landscaper to do anything from planting grass and shrubs to laying out a stone patio. Depending on the complexity of your plan, expect to pay anywhere from $5 to $24 per square foot for landscaping services.
Septic Riser
A septic tank riser is an optional component that costs an extra $300 to $600 to install upfront. It will save you money in the long run by raising your septic tank’s access point to the surface. This makes regular maintenance simpler and less expensive.
Pump Alarm Costs
This optional septic system accessory adds about $500 to your project total. Pump alarms can alert you if there’s a problem with your system, such as unsafe water levels or pump failure, so you can call a plumber before it gets worse. Consult with your septic tank installer to find out if a pump alarm is a good fit for your system.
Replacement Parts
Systems are subject to cracks and corrosion over time. For many homeowners, replacing their septic tank is much more affordable than replacing their entire septic system (which could cost up to $25,000). A tank replacement will cost anywhere from $3,000 to $10,000—but other parts may start to fail and require replacement, too. Here are some common replacements and their associated costs:
Septic distribution box replacement costs $500–$1,500
Pump replacement costs $800–$1,400
Baffle replacement costs $300–$500
Filter replacement costs $230–$280
Tank lid replacement costs $30–$70
Drain field replacement costs $7000
Maintenance
Regular pumping and cleaning are key for the smooth operation of your septic system. You should hire a plumber near you to pump your septic tank every three to five years. On average, most homeowners spend $300 to $600 on septic tank pumping costs. This vital preventative service can save you money compared to the cost of repairs for a malfunctioning system.
Cost to Install a Septic System Yourself
Septic system installation is complex. Mistakes can lead to water pollution, dangerous waste, foul smells, property damage, expensive repairs, higher insurance premiums, and difficulty selling your home. For these reasons, many states require septic tank installation to be completed by licensed professionals.
Even if you live in an area where DIY septic tank installation is legal, you should still leave this high-risk project to a pro. Call around and discuss your needs (and budget) with multiple septic tank companies in your area to determine the best fit.
How You Can Save Money While Installing a Septic System
While DIY septic system installation is off the table in most cases, there are still some tasks you can easily do yourself to save money. Once you’ve selected an installation company, work with them to identify which of the following you may be able to handle on your own:
Coordinate your own soil tests
Obtain the proper building permits (after ensuring that your installer will accept them)
Remove existing landscaping features like trees and shrubs
Dig your own holes and trenches (according to plans laid out by your installer)
Purchasing gravel and other materials
Nick P. Cellucci contributed to this piece.
