How Much Does a Septic System Cost?


Written by:  Howmuchisit.org Staff
Last Updated:  August 8, 2018

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The septic system is composed of a small scale sewage system which is common in areas that have no connection to the main sewage pipes provided by the local government or private corporations.  In fact, according to the American Ground Water Trust, one in three Americans have a septic system.  This system is designed to collect your wastewater and dispose of it.

The cost to install septic system depends on the size of the septic tank, the type of septic system, the complexity of the installation, geographical location and company installing the system.

Septic Systems and Steep Slopes by SoilScience.info, on Flickr
Septic Systems and Steep Slopes” (CC BY 2.0) by SoilScience.info

How much does a new septic system cost?

Overall, the cost of a septic system can range anywhere from $3,000 to $15,000 to have a professional install, depending on the factors mentioned above.  A three bedroom home, for instance, can cost about $8,000 to $14,000 for a 1,000-gallon tank, while a 1,500-gallon tank, which is designed for a home with more than five bedrooms, could cost more than $15,000.  Refer to our table below to see what the average type of septic tank costs for the typical 1,600 square foot home with three bedrooms.

According to Realtor.com, the average three-bedroom home should expect to have a 1,000-gallon tank at a minimum, which can cost $8,000 to $15,000, on average.

Type of Septic TankHow it Works?Average Price
Aerobic unitThis system mixed airs into wastewater, which allows the bacteria to break down the solids quicker. Some units, depending on the model you choose, can also use a fluid with chlorine to disinfect the water.$5,000 to $8,000
Drip irrigationThis system requires a shallow drain field where water will slightly trickle out over a wider area from a pump. When installed, flexible tubing will be piped out to the field.$3,000 to $12,000
Mound systemThis system will be used when the soil is too thin or your soil has too much clay in it. With this system, a pile of sand and gravel will be buried within the drainfield to filter the water as it leaves the tank.$10,000 to $20,000
Sand filterA sand filter will work with both a tank and an aerobic treatment unit. This filter consists of a larger buried box that's filled with sand. As the pump releases water to the top, it filters through the sand before it lands in the drainfield.$5,000 to $12,000
Standard system made of concrete, fiberglass or polyethyleneA conventional system will carry the wastewater from the house, into the tank and then out to the drainfield. This box will commonly made from either concrete, polyethylene or fiberglass. As the water pools in the tank, it will eventually separate and flow out to the field.$5,000 to $11,000

Factors that affect the cost

The type

There are three common types of septic tanks installed:  concrete, steel and fiberglass.  Concrete septic tanks, for instance, are the most common type of tank installed in most households.  This type of system is entirely made of concrete and is usually durable for a few decades.  Steel, on the other hand, isn’t as durable as concrete due to the corroding-prone cover and will be the least popular option because of this.  Lastly, fiberglass is less likely to rust and crack, but it can shift inside the soil over the years.

The size of the tank

The size of the tank will be one of the biggest factors that affect the price.  With any project, the larger the tank is, the more it will cost since more digging and preparation will be required.

Soil conditions

The soil type, depth and water table can affect the tank since some soil may be hard to excavate, while other soil may be harder to support the tank, requiring modifications to be made.   A wet, marshy site and rocky terrain can often be the most expensive soil to work with.

Topography

If the site were to have a slope more than 15 percent, then an alternative system may be required, ultimately increasing the costs.

How much preparation is involved?

Like the size of the tank, you also have to pay close attention to how much digging is involved before the tank is even installed.  Also, if it’s being installed in an area with landscaping present, be prepared to replace it after the tank has been buried.

The professional

With any professional job, the professional you choose can greatly affect the price.  Working with a professional is highly recommended since this is considered a labor-intensive project meant for a team of contractors to perform.

Septic system overview

Before the tank is dug, an expert will come to the site and assess the situation by performing tests and designing a unique system that works for the home.  Installing a septic system typically takes three to six days for the average three to five bedroom home and is usually done right after the home has been built.

During the process, larger construction equipment will be required to dig out the system and lower the tank into the ground.  Due to this, most professionals will recommend you install your septic tank after your home has been built but before you landscape and install your driveway.

All septic systems will work with two parts:  a tank where the solid settles to the bottom and a drain field where the water will dispense.

What are the extra costs?

Soil testing, usually about $300, before the septic tank is dug, will be required to ensure the area is adequate for the tank.   This test will determine the soil’s draining capability, the high groundwater mark and if there’s any sign of bedrock.  With this test, a professional will be able to understand where the best site on your property will be.

A building permit/s will be required in most cities and can usually cost about $200 to $1,000, depending on where you live.

A septic tank needs to be maintained every few years by having it pumped.  Pumping the tank keeps the sludge at the bottom from rising to the top, which if not pumped, can overflow into your yard.  Pumping a tank, on average, can be about $300 to $500.  At the very least, according to Realtor.com, have it checked to see if it needs to be pumped.  Any reputable septic tank pumping service should be able to visually inspect the system and let you know if it’s necessary.

Aero-stream says the average septic tank fails every 15 years, and because of this, you may have to think about costly repairs or even a replacement.

Landscaping, if it were damaged during the dig, may have to be replaced if you choose to do so.

Tips to know:

Consider installing low-flow toilets and being conscious about using the water if you have a tank.  The less water that flows in the tank means the less maintenance you have to worry about.

Understand your local state rules and laws before having a tank installed.

How can I save money?

Since there’s a good chance you’re going to hire a professional, always make sure you get at least three quotes from licensed and insured contractors in your area.  If you don’t have the time, consider using HomeAdvisor.com to have these professionals contact you with a customized quote.


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