For a lot of people out there, a septic tank is an integral part of a plumbing system. In fact, more than 60 million citizens in the US depend on septic systems.
It’s easy to see why septic tanks are installed in an increasing number of properties. It’s noteworthy that having such systems is beneficial to the environment, as they eliminate pollution from surface water. They’re also economically-efficient since they reduce the extra costs of treating wastewater.
However, while plastic septic tanks are lightweight and cheap, they’re not as long-lasting as their concrete counterparts. But concrete tanks can be heavy and expensive, as well.
In this article, we’ll take a closer look at concrete vs. plastic septic tanks. What they are, how they work, what’s the optimal use for each, and how their performance differs?
That’s what we’re going to explore today. Let’s dive in!
What Is A Septic Tank?
A septic tank is an underground tank that’s used for treating sewage. Its role is to perform wastewater treatment.
“Isn’t that what sewage systems are for?” Well, yes. But keep this in mind: Most septic systems are used in rural areas. Usually, there aren’t any centralized public sewer systems in these areas.
By successfully fulfilling its job, a septic tank can result in the following:
- Decrease the risk of transmitting disease
- Decrease human exposure to pathogens
- Help in recharging groundwater
- Decrease large infrastructure costs
How Does A Septic Tank Work?
Here’s what a functioning septic tank does.
- A septic tank takes all the water flowing out of a house
- Once the water gets to the tank, all the grease and oil rises to the top
- Other substances of heavier density (like solids) sink to the bottom
- A layer of wastewater, called effluent, remains in the middle
- The wastewater eventually makes its way out of the tank and sinks into the soil
- The soil treats the wastewater, later discharging it to groundwater
There are alternative systems where effluent trickles through sand, organic matter, or even wetlands. Such systems can be expensive, but suitable for certain environments. For example, a recirculating sand filter system is ideal for installation in sites close to water bodies.
In such a system, the sand filter can be placed either above or below the ground. The effluent is then pumped to the sand filter. As it percolates through the sand, the wastewater is then treated.
Plastic vs. Concrete Performance Comparison
Plastic tanks are convenient and budget-friendly. Moreover, they’re easy to work with since they’re so lightweight. This can prove efficient during transport, but not so much when they’re in the ground. It’s this lightness that causes plastic septic to float and tilt, after all. This 750-gallon plastic septic tank is a good example since it’s not only corrosion and rust-proof, but it’s affordable as well.
On the other hand, we have concrete tanks. This concrete tank is a long-lasting tank that can tolerate driver-over traffic. In general, concrete tanks provide the strength of plastic septic tanks and none of the lightness. They’re quite heavy, which makes installation hard and expensive. But, their heavy weight also anchors them well to the ground, preventing any possible shifts.
Weight
Plastic septic tanks are made from lightweight polyethylene. This quality makes them incredibly easy to transport and install.
In contrast, concrete septic tanks are quite heavy. To put this in perspective, plastic septic tanks weigh about 440.925 lbs (200 kilograms), while concrete septic tanks weigh about 3306.934 lbs (1500 kilograms.)
The heavy load of concrete makes installation both hard and expensive, but it offers more durability than plastic. However, plastic septic tanks don’t require as many employees or as much specialized machinery as concrete septic tanks.
Stability
During heavy rainfall, the soil can get excessively wet. In such cases, floatation can occur in plastic tanks. The results then can vary: The septic tank can suffer anything from leakage to damage.
However, since concrete tanks are so heavy, you can rely on them to remain rooted in their place. You don’t even need to worry about wet soil conditions. Concrete septic tanks won’t even shift or tilt.
State Approval
Plastic septic tanks aren’t approved in all states. So before you think about shopping for one, try to check your state’s official website for approved septic tanks.
However, unlike plastic septic tanks, concrete septic tanks are approved in all 50 states.
Sturdiness
There have been cases where plastic septic tanks were damaged under the pressure of trucks driving over. Drive-over traffic can seriously affect the state of the tank.
With a concrete septic tank, this shouldn’t be a concern. Concrete septic tanks are incredibly sturdy. They’re resilient enough to withstand soil changes and environmental conditions. With the proper maintenance, they can last up to forty years. However, as they age, the quality of their performance goes down.
For this reason, concrete tanks are ideal for areas undergoing property renovations, due to their resilience. Plastic tanks, on the other hand, should be installed in remote areas since they’re low-traffic.
Pricing
Plastic tanks are quite affordable. They’re neither expensive to buy nor to install. A plastic septic tank can be considered a perfect cost-effective solution to your water treatment problem.
But with concrete septic tanks, you’ll have to spend more money. It’s not only purchasing that will incur an expense. Upkeep and repair can be costly due to the tank’s heaviness. Likewise, at the end of the tank’s life, extraction won’t be cheap.
Plastic tanks can be a worthy investment when considering the affordable installation. Such tanks are also suitable for special cases in which tenants wouldn’t occupy a property for a long time. However, a concrete septic tank can last longer than a plastic one.
Final Verdict
Choosing the material of the septic tank is an important decision. But like anything else in life, both concrete and plastic tanks have their pros and cons. Concrete septic tanks are long-lasting and reliable, but they’re unfortunately expensive to purchase and difficult to install.
Plastic tanks share some of their concrete counterparts’ strength, but they’re lighter and generally less stable. They’re also more affordable.