Concrete, Fiberglass, or Plastic? Which is Best for a Septic Tank

You have decided to take your wastewater management in to your own hands. That’s great. Whatever your reason was – you want to cut down on your water utility bills, satisfy your need to be self-reliant or just want to be more environmental friendly – it’s still important to choose a septic tank that will suit your needs the best…

But how can you be sure that you pick the right material? There is so many out there! Well lucky you, instead of going down the endless rabbit hole of information that the internet can be, we gathered the advantages and drawbacks of the 3 most popular tank types.

A photo of some septic tanks on a truck bed.

Pros & Cons of Concrete Septic Tanks

Concrete. Hard, strong, used to build the Roman Empire (well, some of it). This classic material seems to be a fitting choice for your tank. They built to be functional for decades with proper maintenance. The size and shape can be anything. You can order it to be a small piece for your weekend house, or it can sized up to match the requirements of your industrial estate. Being sturdy and solid, you don’t have to worry about damaging it during installing, nor will it float away when the surrounding ground becomes damp. This strength also means that you can put more weight on top of the tank, maybe even drive though the surface with a car (although this isn’t recommended).

But, this durability comes with a price. Even a small 600 gallons (2700 liter) tank can weight up to 6600 pounds (3000 kg)! This means that heavy machinery is a must during installation, which can put a dent in your budget and an unexpected limit on the location. After all the heavy lifting done, you will have to think about the material itself. Concrete is porous. This means water will get into the tiny voids in your tank’s walls, providing a cozy bed for roots and bacteria, leading to cracks and leakage. You can avoid this by lining the surface with a non-porous material, but you will need to replace it periodically. Speaking periodic check-ins; your tank needs to be constantly surveyed for damage. Issues can go unnoticed for months, leading to a tank that needs replacement.

So you managed to catch that crack on the tank in time for a repair? Good! Now it’s time to dig deep into your pocket again, because repairing concrete requires specialized knowledge. You would rather take it out from the ground and put a new one in? That’s going to be costly as well. Remember those heavy machinery during installation? Yes, you will need then again, meaning more specialized machine and manpower.

Pros & Cons of Plastic Septic Tanks

Our good friend from the 50s: Polyethylene. Cheap, easy to shape and lightweight. A plastic septic tank can be a great alternative for concrete when you plan to use it in a place that isn’t reachable with heavy machinery. It’s also a more affordable option. You don’t have to worry about roots gaining a foothold on the side of your tank; plastic is a non-porous material. This also means it won’t leach chemicals into your water, nor will provide a bed for bacteria to grow. Since plastics are lightweight it doesn’t require more than a couple of people to handle it. A 600 gallons Polyethylene tank is only about 250 pounds compared to the 6600 pounds concrete tank. You can transport it in the back of a pick-up truck.

Now the back draws of this lightness is that the tank can ‘float’ when the ground around it becomes saturated with water. You can prevent this by anchoring the tank in a concrete bed. However, the other issue with high groundwater levels is that they can distort or damage your tank. If you don’t create a waterproof casing first then you’re going to have problems. The most common problems are smaller capacity, punctures on the wall, and lids that don’t fit properly.

Pros & Cons of Fiberglass Septic Tanks

Your fiberglass tank carrying all the advantages of their plastic counterpart. It’s cheap, even cheaper than common plastic. It’s lightweight, so it can be installed in hard to reach locations, and even one man can place it into its final position. Installing it couldn’t be easier; put it in the ground, connect the tubes and it’s done! You don’t have to worry about distortion when the tank is empty, because it’s more durable than common plastic. You caught a nasty crack on the side of the wall? Not a problem. You can fix it with a fiberglass repair kit, no special knowledge needed.

Now this tank carries some of the disadvantage of its polyethylene cousin. It requires anchoring so it doesn’t float away, but it doesn’t need to be in a watertight casing. You have to be careful during install, because heavy machinery can puncture or otherwise damage the tank. It is resistant against bending due to water pressure, but you can harm your tank if you put too much weight on top of it. Clear marking above ground is a must, so you can avoid driving through the surface.

Which Septic Tank is the Best Fit for You?

So what do you think, which tank will be the perfect match for you? A large and robust concrete one for your industrial site? You want something small and light for your weekend house made from fiberglass? A polyethylene piece for your rural dream house? After considering all the benefits and disadvantages, you can feel safe that you made the right decision. Or you can give a call to a local Syracuse septic tank contractor!

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