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How much does a septic tank cost?

Average costs are around $6,500, including labor

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Written by Sarah Harris
Edited by Vincent Landino

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    installing septic tank

    Replacing a septic tank usually costs anywhere from roughly $3,000 to $10,000, depending on the type of tank your home needs, the size of your house and the cost of installation. Because of these factors, septic tanks costs can vary widely, and a full septic system can cost much more than just replacing a tank.

    Doing your homework is a good way to make sure you’re getting the right deal. With the right information, you’ll know what to expect and what fair prices for repairs and replacements look like when you start making calls and gathering quotes.

    What is a septic tank?

    A septic tank is an underground structure that treats contaminated water from your home. These tanks are usually made of concrete, fiberglass or polyethylene, and they’re part of a larger septic system that delivers the wastewater to the tank and discharges it once it’s been treated.

    Septic tanks can be more affordable than connecting to a sewer system, and they’re often better for the environment. However, they can require more maintenance and more care regarding what you put down your drains. If you’re building a new house, you may have a choice between a septic system and a shared sewer system, but most homeowners just stick with what their house was built with.

    How does a septic tank system work?

    Generally speaking, septic tanks function by separating floatable matter (like oil) and solids from your home’s wastewater before sending the remaining treated water out into either the soil, sand, organic matter, wetlands or other media. However, the specifics of how a given type of system works will differ.

    In a conventional septic system, the grey water and blackwater from your home flow into the tank. Over time, the solids sink to the bottom of the tank, and fats, oils and grease float to the surface as scum. The scum and sludge are separated from the wastewater, and the treated water is sent to the drainfield for further filtration.

    The drainfield removes harmful coliform bacteria and viruses as the wastewater gets sent through a filtration process involving sand, soil or other means. The wastewater is then continuously filtered as it passes through the earth before entering the water table.

    Types of septic systems

    There are multiple types of septic systems, but the two main options are:

    • Conventional (anaerobic) systems: These underground water treatment systems strain effluent (treated water) through stone or gravel in a drainfield. They’re generally suited to single-family homes, and they’ll usually cost you $3,000 to $8,000.
    • Aerobic systems: These units add oxygen to the tank, which speeds up the breakdown of waste. They can be used in places where conventional systems may not work, but they cost around $10,000 to $20,000 because they’re more complex.

    Alternative system options include:

    • Chamber systems: These systems are a non-gravel alternative to conventional (anaerobic) systems. They’re easier to build and better for locations with higher water tables. Installing a chamber system runs around $5,000 to $12,000.
    • Drip distribution systems: A DDS requires a secondary unit to store the wastewater once it leaves the septic tank, limiting the amount of outflow from the tank. The benefit is that it requires less soil in the drain field. A drip distribution system usually costs between $8,000 and $18,000.
    • Mound systems: A mound system is required if the drainage field has to be elevated above the tank. A pump tank pushes the wastewater up to the drain field, meaning this system requires electricity and more maintenance on average. They cost between $10,000 and $20,000.
    • Recirculating sand filter systems: If your home is on a high water table, then this type of system may be for you. A pump pushes the effluent to a sand filtration system, removing much of the contaminants before reaching the soil. Costs for these systems vary from $7,000 to $18,000.
    • Evapotranspiration systems: These systems are really only for people living in arid environments. Here, the effluent evaporates into the air and never reaches the soil or the groundwater. They run between $10,000 and $15,000.
    • Constructed wetland systems: These systems mimic natural wetlands. They require more space to work properly, but the wastewater is filtered thoroughly. They cost $8,000 to $15,000, but costs increase if you install an aerobic tank.

    Your preferences, household size, soil conditions and property features will influence which is right for you.

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      Signs your septic tank is full

      If you notice any of the following around your home, your septic tank may be either full or broken:

      • Slow drains
      • A toilet that won’t flush or is slow to flush
      • Gurgling noises after flushing the toilet or running water
      • Sewage odor in the yard
      • A very green lawn, specifically around your septic tank
      • Pooling water in the lawn

      Any of these signs could mean that something is wrong with your septic tank, but there’s a big difference between your tank being broken and it being full. Pumping rectifies a full septic tank, and it should only cost you about $300 to $600. On the other hand, a broken septic tank needs to be either repaired or replaced, and those will usually cost you more money.

      How much does it cost to repair a septic tank?

      If your tank isn’t working properly, repairs can run you anywhere up to $1,500. However, your issue might not be with the tank itself but some other part of the septic system.

      It really all comes down to which part is broken:

      • Pump repairs can cost $250 to $400.
      • Filter replacement will run you somewhere in the $200 to $300 range.
      • Baffles cost anywhere from $100 to $900 to fix.
      • Septic lines average around $1,500 to repair, but it’s not unheard of for them to run up to $4,000.

      If you can have your septic tank or system repaired and still get many years out of it, then that’s generally the favorable option. However, not all problems are fixable.

      A septic tank professional should consider the following as they help you determine whether repair or replacement is right for your home:

      • Are puddles forming quickly? Generally speaking, puddles in the yard aren’t too problematic. Puddles in the yard that quickly form overnight are a whole different matter, though. When puddles form slowly, it typically indicates a full septic tank, but it could also mean there’s a problem with the pipes or the leach field. If the puddles are springing up quickly, it points to a more serious problem, such as a cracked tank that you’ll need to replace.
      • What’s your household size? Larger households need larger septic tanks. If your household has grown over the years but your tank has not, it may be a good idea to replace it with a larger tank that can keep up.
      • How often are you needing repairs? An occasional repair isn’t a big deal, but when repairs start becoming a common occurrence, it’s time to reevaluate. A problematic septic system is likely on its way out, meaning you’ll need to pay to replace it.

      Whether you’re repairing or replacing your unit, it’s worth noting that you can dramatically reduce your out-of-pocket expenses if your septic tank is under warranty. While some new septic tanks come with warranties from the manufacturer, a home warranty can cover older units as well. You’ll pay for the coverage, but should something happen with your septic tank, you may only have to pay a relatively small service fee before your warranty company covers the rest.

      How much does it cost to replace a septic tank?

      Expect to spend between $3,000 and $10,000 to replace the septic tank for a single-family home. However, this overall cost really depends on two other numbers: the price of your septic tank and the cost of installation.

      Septic tank prices vary based on the type and size of the tank in question. The tank size you need is usually determined by the size of your household, so there’s not much choice there unless you want to go bigger to accommodate future growth.

      On the other hand, you have more options when it comes to the type of tank you want:

      • Concrete tanks: A concrete tank can cost $700 to $2,000 before installation.
      • Fiberglass tanks: A fiberglass tank typically costs $1,200 to $2,000 before installation.
      • Polyethylene (plastic) tanks: A plastic tank is, on average, the most variable option at $500 to $2,500 before installation.

      Steel tanks are also an option, but they’re less common and prone to rusting.

      How much does it cost to install a septic system?

      Installation costs generally make up 50% to 70% of what you’ll pay to replace your septic tank. That’s why it’s so important to shop around for quotes first to make sure you’re getting a good deal.

      Here’s a breakdown of what your labor costs pay for:

      • Perc test: A perc test evaluates how well your soil absorbs and filters water. It requires the technician to dig a 2- to 3-foot hole, pour water in it and see how fast it dissipates. A perc test will run you around $750 to $1,850.
      • Building permits: The cost of building permits vary depending on your municipality. They typically run between $400 and $2,250, but you may pay more if you install an alternative septic system or you’re in an expensive area.
      • Excavation costs: This should run you $1,200 to $4,500, but this number will increase significantly if you also install a pump or go with the constructed wetland septic system.
      • Electrical: A traditional septic system will not need electrical work, but any system requiring a pump or other mechanical apparatus will require electricity. This cost is hard to determine since your local electrician will set the pricing and their effort depends on how much underground electrical line they have to run.

      If you’re installing a septic system from scratch, you’ll have to pay even more for your drain or leach field and the plumbing to connect your home to the tank. A new drain field can cost up to $15,000.

      How long does a septic tank last?

      Septic tanks usually last 20 to 30 years, but some make it 40 years or more. The longevity of a septic tank depends on what they’re made of and how often they’re cleaned.

      Less-popular steel septic tanks may rust out after 15 years, though many last longer. Concrete tanks have longer life spans, but they can be sensitive to acidic soil. Plastic and fiberglass tanks are less susceptible to the elements, but structural damage is more of a concern with these tanks.

      The other key to longevity in septic tanks is maintenance. Regular pumping and servicing help ensure your tank does its job for years to come.

      Bottom line

      There’s a lot to think about when dealing with septic tank issues. Getting professional advice is important, but it helps to know what to expect so you can make educated decisions.

      Whether you’re budgeting for a new tank or trying to keep your system running, it’s a good idea to shop around, read reviews and get multiple quotes to learn about your options.

      If you’re just planning ahead or worried about septic tank costs down the line, consider a home warranty to help offset the costs. Read up on what they cover and whether they’re worth the money to learn more.

      ConsumerAffairs writers primarily rely on government data, industry experts and original research from other reputable publications to inform their work. To learn more about the content on our site, visit our FAQ page.
      1. United States Environmental Protection Agency (EPA), “Types of Septic Systems.” Accessed September 26, 2021.
      2. United States Environmental Protection Agency (EPA), “How Your Septic System Works.” Accessed October 11, 2021.
      3. United States Environmental Protection Agency (EPA), “How to Care for Your Septic System.” Accessed October 11, 2021.
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