Septic System Cost to Install in a Home

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A proper septic system installed for a home in Tennessee

It’s a topic that many homeowners don’t want to talk about, but how much does a septic tank really cost? The truth is, it can vary depending on how big your home is and how bad the current system needs to be replaced. This article will give you all of the information you need to know about how much a septic tank costs in Tennessee so that you can make an informed decision when buying or selling your home.

Why Your Home Needs a Septic Tank

The septic tank is a French invention that was originally used for sewage treatment. The first tanks were made of concrete and stone, but modern versions are typically constructed with fiberglass or plastic materials.

In residential housing, the city usually treats sewage, but if your Tennessee home isn’t connected to the municipality waste system, you will need a septic tank. Why your home needs a septic tank is because the waste from your house will need to drain into the system, which then filters out all of the solids and liquid before allowing it to reach our groundwater.

A septic tank is how your home gets rid of the wastewater from sinks, toilets, laundry, and showers. It’s an important component of a house in Tennessee- without it, you’ll be paying more for regular plumbing services or emptying cesspools. 

Having a functioning septic tank is especially important if you’re planning to sell your Tennessee property. Updating your septic tank is one of several improvements that will boost your property value and help attract buyers. But that doesn’t go without saying they can be costly to replace, depending on the size and type of septic tank you purchase.

What Size Septic Tank Do You Need?

Septic tank size is usually determined by the number of bedrooms you have. This is used as a way to estimate how much water will flow through the system each day. Generally, more bedrooms equal a larger septic system and higher cost – but these numbers are just estimates and may vary based on local regulations.

Two Bedrooms

A two-bedroom house requires a septic system with a minimum capacity of 750 gallons. However, in many municipalities, the standard requirement is 1,000 gallons for this size home. 

Three Bedrooms

A three-bedroom house needs a minimum of a 1,000-gallon water tank in order to handle approximately 360 gallons per day.

Four Bedrooms

A four-bedroom home requires a larger tank with a minimum volume of 1,250 gallons. It handles around 480 to 600 gallons of water per day.

If you’re unsure what size septic tank you need, you can always refer to the one you already have or get an estimate from a contractor and see what they would recommend. 

Different Types of Septic Tanks

As the cost of living in TN is rising, so is the cost of systems and building materials. However, the total cost of installing or replacing your septic tank is largely dependent on the type of system you choose. Here are some of the most common kinds of tanks:

Fiberglass Tanks

The least expensive septic tank option, costing around $500 to install. Pros include how easy the system is to maintain and how inexpensive it is initially. Cons maybe that fiberglass will deteriorate over time and isn’t a good choice for more than one toilet or bathroom in your home. It’s also not suitable for high water tables because of how quickly moisture can get inside the tank.

Fiberglass tanks are often used with no leach field installation necessary if they’re located lower than the ground level on sloped terrain (less than about 15 degrees) or don’t have an impervious surface near them such as concrete, asphalt, etc., below-grade nearby which would keep rain from wicking into the structure.

Plastic Tanks

This system is less expensive than concrete ones and usually costs around $700 to install. In the long term, they are a good choice for low water usage homes with fewer toilets or bathrooms because plastic doesn’t corrode as steel does. The downside of this type is that it’s not as durable in freezing temperatures (metal can expand up to 40% when frozen), which could cause cracks in your tank walls and leaks into your home from those fissures which can happen in Tennessee because of the colder weather residences experience in the winter season. 

Concrete Tanks

The mid-range septic tank option, costing around $800 to install, is a concrete tank. Pros include how sturdy the system is and how long it lasts (usually 30+ years). Cons maybe that concrete does not work well with freezing temperatures, so you would need to take precautions against cracks in your tank walls and leaks into your home from those fissures during the winter months in Tennessee. They also require a leach field installation which costs extra.

Concrete systems are often used when no other type will do for high water usage homes with more than one toilet or bathroom. They can handle up to 1200 gallons per day on sloped terrain, impervious surfaces below grade nearby such as concrete, asphalt, etc., and even on level terrain.

Below-ground Tanks

The most expensive septic tank option, costing around $1000 to install for the typical homeowner. Pros include how low maintenance and sturdy it is – these systems are less likely to have a failure than any other type of system over time because they’re not exposed to freezing temperatures or heavy rains (which would otherwise cause cracks in your tank walls). Cons may be that this system requires more land space and will cost more upfront, with installation costs usually between $3000-$4000+.

Below-ground tanks are often used when there’s no way you can accommodate an above-ground system due to the limited amount of usable land available at where your house was built; high water usage home with lots of toilets or bathrooms; and when the property is too close to a water table for concrete, fiberglass or plastic tanks.

Steel Septic Tanks

Another pricey option is a steel septic tank system, costing around $2000 to install. Pros include how long they last (usually 30+ years) and how strong the material is. Cons may be that steel tanks are not as low maintenance-prone or worry-free as fiberglass if you live in areas with higher water tables because even a tiny crack can cause corrosion over time and lead to leaks into your home from those fissures.

Steel is often used when there’s no other option for high water usage homes with more than one toilet or bathroom; on sloped terrain like less than 15 degrees in elevation; impervious surface below-grade nearby such as concrete, asphalt, etc.; or level ground construction without area of concern near it like an area at an elevation level higher than the tank.

The Cost of Installing a Septic Tank

It’s not cheap to install a septic tank. The average cost to put in a new septic system is $3,280 to $9,550. A basic septic system for a 3-bedroom home will cost $3,918 on average, with most homeowners spending between $3,280 and $5,040. When you install a system with two alternating pumps, expect to pay $9,500 to $15,000.

Cost Factors to Install

Installing a septic system is expensive because of the amount of labor involved in doing it correctly. From start to finish, the entire project could take up to three weeks or longer, depending on the permit processing and the complexity of the system you need for your property.

  • Soil testing – A deep hole percolation test by a qualified engineer costs at least $1,000 but ranges between $1,000 to $2,000. Testing will reveal the type of soil in the area and what depths the different layers are at, how deep each layer is, and how well suited the area is to filter and drain from the system with the combination of layers. Positive results from the survey and test will also allow you to get approval for the drain field (also called leach fields or leach drains).
  • System design – The septic system design will generally take between 2–3 weeks to design and cost an average of $600, depending on your location and the complexity of the system. Use the same engineer to do both the percolation test and the system design, as he/she might not accept the test results from the percolation test if done by someone else.
  • Clear the land – Land clearing costs around $950 on a quarter-acre for light clearing on flat ground without rocks.
  • Install and connect pipes and tanks – To take wastewater from the house to the septic tank costs $25 to $33 per linear foot for excavation, installation, and backfill; and an average of $1,000 to $1,500 for the tank.
  • Leach Field – A drain or leach field will typically cost between $2,000 to $10,000. Lay the filtration materials or leach field – $9–$12 per linear foot. Then, add $25–$33 per linear foot of vitrified clay pipe to the septic tank from the house.
  • Inspection and testing – Pass all checks and final inspection and testing – Building permits cost about $250 to $450, and your local health department will determine which permits are required.
  • Pump Alarm – Add $720 for a high-water or pump failure alarm.
  • Landscaping costs – Include the fees of any landscaping needed once the tank is installed and dirt has been backfilled over it.

Cost to Install a Septic System Leach Field

The average cost of installing a septic system drain or leach field is $2,000 to $10,000. Septic sewer drain fields or leach lines are built with unsaturated paper, piping, and gravel. The fields are excavated, and 4 PVC pipe is laid in 3′ deep by 1′ wide trenches, after which it’s backfilled, and excess soil is disposed of properly.

  • With 12″ gravel base – $30/LF
  • With 24″ gravel base – $11/LF
  • With 36″ gravel base – $30/LF
  • Add for pipe laid 6′ deep – $20/LF

Septic System Permit Cost

You’ll need your permit from local authorities to allow the construction of your new septic system. Expect to pay about $250–$450. In addition, it’s usually required to need a site plan: a scale diagram of your land which details the location of the house, outdoor elements (like a detached garage, any walkways, any swimming pools), and the location of the septic system. You can apply for the permit yourself, or your local contractor can include this in the quote. On average, the permit will take about 1–2 weeks to secure, and costs include the inspection during construction and after this work is complete.

installation of septic system for a home

Septic Tank Costs

The cost of your septic tank will depend on the material it’s made from. Concrete tanks tend to be the most expensive and range between $720 and $2,050. Fiberglass tanks are cheaper than concrete tanks but more expensive than plastic because fiberglass is denser. They typically range from around $1,600-$2,000 in price, while plastic costs around $830-1,900 dollars on average. 

Concrete Tanks

Concrete septic tanks are the most common type in use in the United States due to their durability and relative affordability. Prices for precast concrete systems range from $720-$2,050, with an average cost of about $1,500-1,600.

Concrete Septic Tank Cost

Tank SizeAverage Cost
1,000 Gallon$815-$1,250
1,250 Gallon$945-$1,235
1,500 Gallon$1,100-$1,520

Concrete is an excellent choice of material for a septic tank, as it’s durable and resists damage — but concrete tanks will crack unless adequately reinforced. This requires expert equipment and more labor because the tank weighs so much.

Stainless Steel Septic Tank

Despite the durability and strength associated with steel, metal septic tanks will eventually rust and collapse and will likely won’t outlast your neighbor’s concrete tank. Because of this, and increased regulations by local authorities, they are used less and less, and in many regions are likely only to be found in existing systems already installed.

Fiberglass Septic Tank

Similar to plastic septic tanks, fiberglass tanks are lighter and, therefore, easier to install. However, they cost an average of $1,600 to $2,000 for an average 3–4 bed Tennessee home. Fiberglass also won’t deteriorate while underground, nor will it attract the growth of as many algae because of its nonporous qualities. Furthermore, it won’t expand and contract either in the way concrete does so that it won’t develop cracks.

Fiberglass Septic Tank Cost

Tank SizeAverage Cost
1,000 Gallon$1,600
1,250 Gallon$1,810
1,500 Gallon$1,975

Plastic Septic Tank

Plastic or polyethylene septic tanks are cheaper to buy and install because they are lighter, costing an average of $800 to $2,000. They aren’t prone to cracking, but they can sometimes break under pressure or in changing soil conditions. In some states, they aren’t approved for use. However, in Tennessee, they are authorized to use.

Plastic Septic Tank Cost

Tank SizeAverage Cost
1,000 Gallon$830-$1,420
1,250 Gallon$1,150-$1,690
1,500 Gallon$1,270-$1,900

The installation process to replace a septic tank typically takes two days with professional contractors who are experienced in this type of project. You should also call around for prices before selecting one because they can vary quite drastically due to geographic location and size requirements: some installers may not service areas outside Knoxville city limits so check their website first.

Final Takeaways

Replacing or installing a new septic tank can be a big undertaking, especially financially. 

If you’re looking at replacing your tank while trying to sell your Tennessee house, you’ll want to correct any problems before showing your home. Not only could advertising that you’ve installed a new septic system attract buyers, but it may increase your property value. Unfortunately, though, there isn’t a guarantee you’ll get a full return on your investment. 

However, if you’d rather not spend the time or money, another alternative is to sell your house as-is to one of the companies that buy houses in Knoxville. By selling as-is, you’ll be able to “sell my house fast in Nashville,” Knoxville, or Chattanooga without replacing your septic tank and dealing with the extra expense before putting your place on the market.

Feel free to contact this “buy my home Tennessee” company – Nexus Homebuyers if you’d like to sell your house as-is, no repairs required, and no realtor commissions. They can make you a no-obligation cash offer for your home and close in as little as 7-days. So if you’re feeling overwhelmed about selling your house and paying to replace a septic tank, don’t be; give Nexus Homebuyers a call instead and avoid the hassle. 

2 Responses

  1. I love how you said that a house with two bedrooms requires a septic system that has a minimum capacity of 750 gallons. My husband and I live in a two-bedroom home and we want to have a septic system installed. We’ll be sure to find a company that can install the right size septic system for our house.

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