Plastic vs. Concrete Septic Tanks (Key Difference & Pricing)

So you’re caught in the “plastic vs. concrete septic tanks” dilemma, huh? You’re not alone—according to a recent survey, 65% of homeowners find it challenging to choose the right septic tank material. Let’s dive into the nitty-gritty to help you make an informed decision.

If you prioritize affordability and ease of installation, go for a plastic septic tank. If durability and longevity are more important, a concrete tank is the better choice. Both have pros and cons, so consider your specific needs and environment.

Stick around as we unravel the pros and cons of each material, helping you choose the septic tank that’s a perfect fit for your home and lifestyle.

Plastic Septic Tanks – Key Takeaways

CostMore affordable than concrete tanks.N/A
MaintenanceLower maintenance, installation, and removal costs.Requires more frequent maintenance for proper function.
InstallationEasier and quicker to install due to lightweight.Not as sturdy as concrete tanks.
PortabilityMore transportable and compact.Sensitive to soil and environmental changes.
DurabilityImmune to water-based corrosion and rust. Watertight seal.More prone to damage like cracks or breaks.
HygieneMore hygienic than concrete tanks.N/A
AvailabilityReady-to-install options available.Not approved for use in all areas.
StabilityN/AMay float if water level rises, risking damage to plumbing.
Pros and Cons of Plastic Septic Tanks

Understand The Legal Aspect

Legal Regulations Surrounding Septic Tanks

Understanding the legal landscape is crucial when choosing between a plastic and concrete septic tank. Local building codes and environmental regulations often dictate what type of septic tank you can install. Always consult local and state guidelines to ensure you’re in compliance.

Legality of Plastic Septic Tanks

Plastic septic tanks are generally accepted in many jurisdictions, but not universally. They often need to meet specific standards, such as the American National Standards Institute (ANSI) or International Organization for Standardization (ISO) certifications. Some localities may restrict their use, especially in environmentally sensitive areas.

Legality of Concrete Septic Tanks

Concrete septic tanks are widely accepted and are often the go-to choice for municipal systems. However, they too must meet stringent building codes and standards. Unlike plastic tanks, concrete ones are usually permitted even in areas with strict environmental regulations due to their durability and longevity.

Permits and Documentation

Regardless of the material you choose, you’ll likely need a permit for septic tank installation. This often involves soil tests, site evaluations, and sometimes even public hearings. Keep all documentation handy, as you may need to produce it for legal reasons or when selling your property.

Legal Consequences of Non-Compliance

Failure to comply with local and state regulations can result in hefty fines, legal action, and the potential removal of your septic system. Non-compliance isn’t just a legal issue; it can also lead to environmental damage, posing risks to local water sources and wildlife.

By understanding the legal implications of your choice, you can make a more informed decision between a plastic and concrete septic tank. Always consult local regulations and consider hiring a legal advisor to navigate the complexities of septic tank laws.

Factors That Affect Environmental Compatibility

Soil Compatibility

Different types of soil have varying effects on septic tanks. Sandy soil, for instance, offers better drainage but may require more frequent maintenance. Clay soil, on the other hand, may not drain as well, affecting the efficiency of the septic system. Knowing your soil type can guide you in choosing between a plastic and concrete tank.

Soil compatibility plays a pivotal role in choosing between plastic and concrete septic tanks. Sandy soil, known for excellent drainage, pairs well with both types but may require frequent maintenance due to rapid leaching. Clay soil, with its poor drainage, can be challenging for both plastic and concrete tanks, often necessitating additional drainage solutions like a drain field.

Soil Type for Septic Tank
Soil Type for Septic Tank

However, concrete tanks have an edge here due to their weight, which prevents shifting. Loamy soil, a balanced mix of sand, silt, and clay, is ideal for any septic tank, offering both good drainage and stability. In contrast, rocky soil can be problematic for plastic tanks, which may get punctured, making concrete a more resilient choice.

Soil pH also matters; acidic conditions can corrode concrete tanks, while plastic remains unaffected. For areas with high water tables or wetlands, the stability of concrete tanks makes them the preferred choice. Understanding these soil-tank interactions is crucial for the longevity and efficiency of your septic system.

Tree Root Intrusion

Tree roots can be a significant issue for septic tanks, especially older concrete ones. Roots can infiltrate and damage the tank, leading to costly repairs. Plastic tanks are generally less susceptible to root intrusion due to their seamless construction.

Water Table Impact

High water tables can cause plastic tanks to “float,” leading to system failure. Concrete tanks, due to their weight, are less likely to be affected by high water tables, making them a better choice in such environments.

Carbon Footprint

Concrete tanks are resource-intensive to produce, contributing to a higher carbon footprint. Plastic tanks, although made from non-renewable resources, usually have a lower carbon footprint due to lighter weight and easier transport.

Wildlife Impact

Improperly installed or leaking septic tanks can contaminate local water sources, affecting both plant and animal life. Both types of tanks need to be installed and maintained correctly to minimize environmental impact.


Concrete is generally more sustainable than plastic, as it’s made from abundant natural materials. Plastic tanks, although less sustainable, are often made from recycled materials, which somewhat mitigates their environmental impact.

Understanding the environmental compatibility of your septic tank choice is crucial. It’s not just about meeting legal requirements; it’s also about being a responsible steward of the environment. Always consider the long-term ecological impact of your decision.

Plastic Septic Tanks
Plastic Septic Tanks

How To Choose Between Concrete Or Plastic Septic Tank

The section below will dive deeper into the different factors that you should consider when choosing a septic tank type. Depending on your needs and budget, one could prove better suited for you than the other.


When it comes to affordability, plastic septic tanks have the advantage. You can expect to pay several hundred dollars less for a plastic septic tank due to the inexpensive materials used to manufacture them.

Plastic septic tanks will also incur far fewer repair costs over time due to their ease of maintenance. This makes them a much better choice if cost is a major factor in your decision. Because of the nature of concrete septic tanks, they can be costly to both install and remove once the lifetime of the tank has expired.  

When issues arise with a concrete septic tank, they can wind up being quite costly. Since concrete is prone to water damage, some parts of the septic tank could wind up needing to be replaced entirely. Size is another important thing to consider and will be covered in the next section.


Before choosing a septic tank type, you need to be sure of the size, measurements, and specifications of your old tank. This will ensure that you purchase the right tank size and help avoid issues during installation.

When sizing a septic tank, it is usually based on how much water you expect to consume per day. If you are sizing a septic tank for a household that will not exceed 500 gallons of water per day, an 850-gallon septic tank is likely appropriate.

Keep in mind the weight specifications associated with the size of the septic tank you are considering. Bigger septic tanks can weigh much more than ones with lower capacities. In some cases, larger-sized plastic septic tanks can weigh up to 500 pounds. Larger concrete septic tanks can commonly be found weighing over 8000 pounds.

Once you have made a note of the measurements of your old tank, you can begin to consider other factors like life expectancy. This will be covered in more detail below.

Ease Of Installation

If ease of installation is a major concern, plastic septic tanks would be a better option. Concrete septic tanks are much heavier and harder to manoeuvre, often calling for a specialist to aid in the installation. Plastic septic tanks can be purchased already set up and can easily be installed on your own.

You should also consider any issues that could arise during the transportation process when bringing home your septic tank. Concrete septic tanks will be much more difficult to transport yourself. This could mean incurring high shipping costs if you are not able to do it yourself.

Sketch of the correct septic tank
Detailed sketch of the correct septic tank and water catchment, with plans.

Plastic septic tanks, on the other hand, are much easier to transport due to their relatively lightweight. In addition to installation concerns, life expectancy is another major factor. This will be covered in the section below.

Permits and Documentation

When it comes to installing a septic tank, whether plastic or concrete, you’ll invariably encounter the need for permits and documentation. Local and state regulations often require homeowners to obtain a permit for septic system installation. This process usually involves a series of steps, including soil tests and site evaluations, to ensure the proposed system complies with environmental and safety standards. In some cases, you may even need to attend public hearings, especially if your property is near environmentally sensitive areas like wetlands or water bodies.

Keeping a meticulous record of all permits and documentation is not just a bureaucratic formality; it’s a legal necessity. These documents may be required for future property transactions or could be requested during random inspections by local authorities. Failure to produce the necessary permits can result in legal repercussions, including fines and forced removal of the septic system.

Understanding the permit and documentation requirements in your jurisdiction is not just a step in the installation process; it’s a continuous responsibility that extends for the life of your septic system.

Concrete Septic Tanks
Concrete Septic Tanks

Life Expectancy

Concrete septic tanks have an advantage when it comes to life expectancy. You can expect a concrete septic tank to last up to 40 years when properly maintained. Plastic septic tanks generally last around 25-30 years, depending on how well they are maintained and installed.

The increased life expectancy of concrete septic tanks is mainly due to their increased resistance to environmental changes. This will be covered further in the section below.


Concrete septic tanks have another advantage when it comes to durability. Concrete septic tanks are able to last significantly longer than plastic because of their innate resistance to environmental changes. Issues like soil shifts and growing tree roots will not affect concrete septic tanks.

Plastic septic tanks are extremely susceptible to these types of issues and can crack and break under the pressure of the soil. This means that plastic tanks need to be inspected and maintained much more frequently.

Concrete septic tanks are much stronger and will require less maintenance. If you are placing your tank in an area of heavy traffic, it is highly advised you consider a concrete septic tank that can support the weight.

You will need a more durable septic tank, depending on your soil type. This will be discussed in more detail below.


Plastic septic tanks are generally easier to clean than concrete. This is because plastic septic tanks tend to be more hygienic in general. It is advised for either of the septic tank types that you hire a professional to service your tank when it needs cleaning.

Cleaning Septic Tanks
Cleaning Septic Tank

While you could technically drain the tank yourself, it would be a complicated process involving tools that most do not have readily available. Keeping your tank clean is vital to ensuring they work properly and do not encounter issues. The likelihood of issues will be covered in the next section.

Likelihood Of Issues

You could possibly experience issues with both septic tank types, each stemming from certain disadvantages in their design. For example, plastic septic tanks commonly encounter an issue called “float”.

This refers to when the water level rises and causes the tank to shift, potentially damaging the whole plumbing system in the process. Because of the high potential for damage to occur due to elemental changes, it is important that plastic septic tanks be regularly maintained and inspected.

While concrete septic tanks are not susceptible to float, they are more vulnerable to corrosion and other water damage. This can cause damage to the infrastructure of your tank, which can be extremely costly to repair.

If a concrete septic tank has a break too severe, it could wind up having to be replaced entirely. Luckily, most cracks and small breaks are easily repaired.


Lastly, you should consider the warranty policy included with any septic tank that you are planning on purchasing. If an extended warranty is offered, it is advised that you use it to help protect your investment. A good warranty can help cover maintenance costs and, in some cases, replace your tank in the event of an issue.

Most septic tanks that you purchase will come with a limited one-year warranty. This warranty generally covers minor repairs for up to a year after the purchase date. Extended warranties can usually be purchased by extending the coverage time up to five years or more.

Septic Tank Sizes
Septic Tank Sizes


In wrapping up, the choice between plastic and concrete septic tanks boils down to what you value most. If you’re looking for a cost-effective, easy-to-install option, plastic is your go-to.

On the flip side, if you’re after durability and a long lifespan, concrete is the way to go. Each material has its own set of advantages and drawbacks, so your individual needs and the environmental conditions of your property will be the ultimate deciders. Make your choice wisely, considering all the factors we’ve discussed.


  1. Septic System Installation Guide – A comprehensive guide on how to install different types of septic tanks.
  2. Legal Guidelines for Septic Tanks – A document outlining the legal aspects of installing septic tanks.
  3. Environmental Impact of Septic Tanks – A study on how different materials affect the environment.

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