Updated October 2026. Lifespans and tank prices from the U.S. EPA and HomeServe; check your local code for approved tank types.
Concrete septic tanks are heavy, resist floating in a high water table and often last the longest, but they cost more to install and can crack as they age. Plastic (polyethylene) tanks are cheaper, lighter and do not rust or crack easily, but they can float or shift in wet ground unless anchored, and they cannot sit under driveways. For most homes, the right choice depends on the water table, site access and what your local health department approves.
Concrete vs plastic septic tanks compared
| Concrete | Plastic (polyethylene) | Fiberglass | |
|---|---|---|---|
| Typical lifespan | About 40 years (HomeServe); the EPA says 50 years or more | 30 years or more (HomeServe) | 20 to 30 years (HomeServe) |
| Tank price, before installation | $700 to $2,000 | $500 to $2,500 | $1,200 to $2,000 |
| Weight and install | Very heavy; needs a crane or large truck | Light; can go where trucks cannot | Light |
| High water table | Weight keeps it in place | Can float; needs anchoring | Can float; needs anchoring |
| Cracking and corrosion | Can crack and corrode with age or poor concrete | Rust-proof; can deform under heavy loads | Rust-proof; can be damaged during installation |
| Driving over it | Possible if the tank is rated for traffic | No | No |
Tank prices are HomeServe ranges for the tank alone, checked October 2026. Installation, permits and the drainfield cost much more.
Advantages of concrete septic tanks
- Weight keeps the tank from floating or shifting in wet soil.
- Long life when the concrete is good quality: the EPA says a concrete tank may last 50 years or more.
- Can be built for vehicle traffic when the design calls for it.
- Widely accepted by health departments.
Disadvantages of concrete septic tanks
- More expensive to deliver and install because of the weight.
- Can crack from age, heavy loads or ground movement, and sewer gases corrode the concrete above the water line. See how to fix a cracked septic tank.
- Harder and costlier to repair or remove.
Advantages of plastic septic tanks
- Lower tank price and cheaper installation, since no heavy equipment is needed.
- Easy to carry to remote lots, steep sites or backyards with limited access.
- Do not rust or corrode, and resist cracking.
Disadvantages of plastic septic tanks
- Light weight means a plastic tank can float or tilt in a high water table, especially if it is pumped when the ground is saturated. Installers anchor them in wet soils.
- Can deform or crack under heavy loads, so they must stay away from driveways and parking areas.
- Not every model is approved in every state or county.
Replacing or installing a septic tank?
The right tank depends on your soil, water table and local permit. Talk to a local septic company about options and a quote.
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Which septic tank material should you choose?
| Your situation | Usually the better fit |
|---|---|
| High water table or wet soil | Concrete, or plastic with anchoring done to the maker instructions |
| Hard-to-reach lot where a truck cannot get close | Plastic or fiberglass |
| Tank near a driveway or where vehicles could pass | Concrete rated for traffic, or move the tank location |
| Lowest upfront cost | Plastic, if your county approves it for your site |
| Longest expected life | Well-made concrete |
Tank size matters as much as material. See how big of a septic tank you need and our 1,000 gallon septic tank guide.
What about steel septic tanks?
Steel tanks are rarely installed now. HomeServe gives them an average life of about 25 years and warns that steel can rust through and collapse, which is a safety hazard. If you have an old steel tank, have it inspected and plan to replace it. See types of septic tanks.
Quick answers
Do concrete septic tanks last longer than plastic?
Usually. HomeServe puts concrete at about 40 years and plastic at 30 years or more, and the EPA says a concrete tank may last 50 years or more. Installation quality and maintenance matter as much as the material.
Do plastic septic tanks float?
They can when the water table rises or the tank is pumped in saturated ground. Anchoring and pumping in dry weather prevent it.
Can you drive over a plastic septic tank?
No. See can you drive over a septic tank for what concrete tanks can handle.
Are plastic septic tanks allowed everywhere?
Not every model is approved everywhere. Health departments keep lists of approved tanks, so check before you buy.
Sources
- U.S. EPA, Why maintain your septic system
- HomeServe, Your guide to septic tank materials
- InspectAPedia, Concrete septic tanks
- U.S. EPA, How to care for your septic system