I’m often asked which septic tank material is better, concrete or plastic. This has always been a topic of debate, but I have compiled all the information you need to compare the two and decide for yourself which is best.
Plastic septic tanks are best for someone looking for an affordable septic tank that is easy to install. A concrete septic tank would be better suited for someone who is not concerned with cost but wants to most durable septic tank possible. Both have key advantages and disadvantages over the other in certain circumstances.
The rest of this guide will cover the advantages and disadvantages of both types so you can make an informed choice when choosing a septic tank type for your home or business.
Plastic Septic Tanks
Listed below are several of the major advantages and disadvantages of plastic septic tanks. Plastic septic tanks are a more affordable option to consider, but there are circumstances where a concrete septic tank is more appropriate.
Advantages
- Much more affordable than concrete tanks.
- Fewer maintenance, installation, and removal costs.
- They are easier to install due to their lightweight, requiring less time and equipment.
- They are much more transportable and compact than concrete septic tanks.
- Immune to water-based corrosion and rust, and provide a watertight seal.
- Far more hygienic than concrete septic tanks.
- Most plastic septic tanks can be purchased, set up and ready to install.
Disadvantages
- They are not as weight resistant or sturdy as concrete septic tanks.
- More sensitive to changes in the soil, environment, and other external conditions.
- More prone to damage, including cracks or breaks.
- Require more frequent maintenance to ensure proper functions.
- May float if the water level rises, potentially damaging your plumbing system.
- Not approved for use in all areas.
Concrete Septic Tanks
Listed below are the major advantages and disadvantages of concrete septic tanks. While they are a more costly option, they are generally more durable and have much greater resistance to external factors.
Advantages
- They are much more durable than plastic septic tanks.
- Greater resistance to varying environmental conditions and more environmentally friendly compared to something like a cesspool.
- If well maintained, a longer lifespan, with some concrete septic tanks lasting up to 40 years.
- Are not at risk of floating due to rising water levels due to extra weight.
- Approved for use in all areas.
Disadvantages
- More expensive to install, repair, and remove.
- They are much more difficult to transport due to their weight.
- Not as serviceable as plastic septic tanks.
- More susceptible to corrosion, cracks, and breaks.
- More difficult to install than 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.
Budget
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.
Sizes
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.
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.
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.
Durability
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.
Soil Type
The type of soil covering your septic tank is another major thing to consider. If the soil has high levels of acid present, this could cause faster corrosion for concrete septic tanks. Because of this, it is advised that you have your soil’s acidity levels tested before installing a septic tank.
You should also be aware of the firmness of the soil. If the soil is extremely dense, the weight could cause enough pressure to crack a plastic septic tank. Once you have determined your soil conditions, you can consider other important factors like ease of cleaning. This will be covered below.
Cleaning
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.
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.
How Much Does A Septic Tank Weigh?
The average plastic septic tank weighs around 275 pounds, while concrete septic tanks weigh around 10,220 pounds. The actual weight of your tank will vary depending on the size that you have purchased. Smaller plastic septic tanks can be found weighing as little as 90 pounds and up to 500.
Larger concrete septic tanks can weigh up to 8500 pounds. Septic tanks with larger weights are typically intended for industrial or commercial use, with home septic tanks weighing much less. You should be sure of the exact weight of any septic tank you are planning to purchase.
This will ensure that you do not encounter issues when transporting the tank due to the weight.
Which Septic Tank Should I Choose: Concrete Or Plastic?
If you are after the most affordable septic tank available and ease of installation and transport is a major factor for you, plastic septic tanks would be a smart choice. If you are less concerned with cost and installation and want a septic tank that can handle heavy soil and environmental challenges, a concrete septic tank is what you need.
That being said, it is important that you consider all of the factors detailed above before making a decision. This will ensure that you wind up with a septic tank that meets your needs. As mentioned above, installing a septic tank without proper planning can cause damage to your tank, yard, and plumbing system.
Best Septic Tank Brands
There are several septic tank brands to choose from, but three of the most popular are Orenco Systems, Chem-Tainer, and AK. These three brands are the current leaders in the industry and produce some of the highest-quality septic tanks in the United States.
You likely have several local septic tank providers in your area as well. You should check online reviews for septic tank brands located in your area if you are interested in being serviced locally.
Warranty
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.
Conclusion
The best septic tank type for you will largely depend on your needs and environment settings. Things to consider are soil quality, estimated water usage, and cost efficiency. If you are looking for an affordable and easy-to-install tank, a plastic septic tank is what you are looking for.
If you are looking for the most durable septic tank possible, you would likely be better suited to a concrete septic tank. No matter which you choose, it is important that you plan the installation carefully to ensure you do not have any issues.
Ruben has a diverse background in the home services industry, with experience running a construction company, a kitchen and bath showroom, and a moving and relocation company. This breadth of experience has provided him with a wealth of knowledge and expertise in various areas of home improvement in general and specifically in the heating and plumbing niche.