Your Guide to Septic Tank Materials

If you’re redesigning your kitchen or bathroom, you'll probably expect to choose materials for your countertops and floor, but it might surprise you to learn that you can also select what materials your septic tank is made from.

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Septic tank materials range from plastic to steel. Each has advantages and disadvantages you’ll want to consider before deciding.

What Materials Are Commonly Used for Septic Tanks?

Depending on your septic tank design, there are four different materials to choose from: plastic, concrete, fiberglass and steel. Choosing the right material for your waste disposal needs can make a difference in how well your septic system functions and how long it lasts. Here’s a look at the four common septic tank building materials and their pros and cons.

Concrete

Precast concrete septic tanks are large and exceptionally strong and can be used for either homes or businesses. These durable containers typically have a lifespan of about 40 years if they’re properly maintained. However, like other materials, concrete has both advantages and disadvantages that should be weighed before choosing this option.

Advantages of a concrete septic tank include:

• Weight. Concrete septic tanks are heavy, so they won’t float during heavy rains. This can be particularly important if you live in an area with a high water table.

• Large holding capacity. Concrete tanks typically have a larger holding capacity than tanks made from other materials, so you won’t have to pump them as often.

Disadvantages of a concrete septic tank include:

• High installation costs. Due to a concrete tank's size and weight, installation involves the use of heavy equipment, which can increase overall costs.

• Repair difficulties. If a concrete tank sustains damage, it can be difficult and costly to repair.

• Cracking. In extreme temperatures, concrete tanks are susceptible to cracking, particularly if low-quality concrete was used in their construction.

• Corrosion. As they age, concrete tanks can be prone to corrosion.

Concrete Septic Tank Cost

Depending on its size, a concrete septic tank can cost anywhere from $700 to $2,000 (CAD 970 to CAD 2,773).

Plastic

Plastic septic tanks, which are made of polyethylene plastic, are a lightweight alternative to concrete tanks. These versatile tanks typically have a lifespan of 30 years or more, and they come in various shapes and sizes, including low-profile models and portable units suitable for construction sites or RV use. However, plastic receptacles can float in areas that have a high water table or experience heavy rainfall, so they may need to be anchored.

Advantages of a plastic septic tank include:

• Maneuverability. Because plastic tanks are lightweight, they're easy to handle, which makes installation and removal simple.

• Cost. Plastic is the most economical material to use for septic tanks.

• Chemical and corrosion resistance. Plastic tanks are rustproof and resistant to chemicals. They don’t crack easily.

Disadvantages of a plastic septic tank include:

• Susceptibility to pressure. Plastic can warp or explode if subjected to extreme pressure, so these tanks shouldn’t be placed in areas where people drive or park vehicles.

• Susceptibility to weather damage. Plastic tanks are easily damaged in severe weather conditions and other natural disasters.

Plastic Septic Tank Cost

Depending on their size and shape, plastic septic tanks typically range in price from $500 to $2,500 (CAD 693 to CAD 3,466).

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Fiberglass

Fiberglass tanks are made with fiber-reinforced plastics. Although they’re lightweight and easy to handle, like traditional plastic septic tanks, the glass fiber reinforcement makes them substantially stronger. Depending on the specific composition of the fiberglass, the manufacturing process and its maintenance history, a fiberglass tank can last between 20 and 30 years. However, like plastic tanks, they need to be anchored to keep them from floating if the water table gets too high.

Advantages of a fiberglass septic tank include:

• Maneuverability. Because fiberglass tanks are lightweight, they're easy to haul and install, which makes them ideal for areas with limited access to large trucks or heavy equipment.

• Weather resistance. Fiberglass holds up under extreme weather conditions, so these tanks won’t rust or crack.

• Resistance to root intrusion. Grass and tree roots typically can't break through fiberglass, so you'll have a minimal risk of root-related clogs and damage.

Disadvantages of a fiberglass septic tank include:

• Susceptibility to damage caused by shifting. Fiberglass tanks can easily be damaged during installation or if they shift due to floating or ground settling.

Fiberglass Septic Tank Cost

Depending on their size and shape, fiberglass septic tanks typically range in price from $1,200 to $2,000 (CAD 1,664 to CAD 2,773).

Steel

If you have an older home, you may have a steel septic tank. However, most modern contractors won't install one because it can rust through and collapse, becoming a real safety hazard. Steel septic tanks have an average lifespan of 25 years. If you have a steel tank, you should have it professionally inspected regularly to identify minor damage before it worsens and creates dangerous conditions.

All CAD conversions are based on the exchange rate on the date of publication.