What is the Difference Between a Septic Tank and Cesspool?

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Difference Between A Septic Tank and Cesspool

If you are new to septic tank systems you may have a lot of questions about what they are and how they operate. One of the confusing questions many people have are how are septic tanks different from cesspools? That is exactly what we are going to cover in this article.

How are septic tanks different from cesspools? Septic tanks and Cesspools are both onsite waste management systems, however, they differ because septic tanks are designed to process and treat the wastewater before releasing it back into the environment, whereas cesspools do not treat the wastewater. 

In the rest of this article, we will take a closer look at similarities between septic tanks and cesspools as well as what their differences mean for you and your home. We will look at the differences in how Septic Tanks and Cesspools are:

  • Designed
  • How they function
  • Maintenance
  • Cost

What is the Difference in How Septic Tanks and Cesspools are Designed?

Let’s take a look at how septic tank systems are designed versus the design of cesspools.  This is essential in understanding other differences between the two waste disposal systems like how they function and the maintenance required to keep them operating correctly.

Septic Tank Systems Design

New Septic Tanks are usually constructed of a watertight material like concrete, fiberglass, or plastic. The Septic tank is designed to take sewage from the house and have it enter the Septic tank through the inlet pipe. The Sewage is then held in this tank until the processed effluent runs out of the tank through the outlet pipe into the absorption area.  You can see an example of a septic tank design below.

Schematic of a septic tank

Cesspool Design

Let’s compare the design of Septic tank above with that of a cesspool to see how they are designed differently. A cesspool is designed as a pit that is lined with concrete or stone. It is meant to hold the sewage into the pit and does not process or treat the water. In most areas, cesspools are considered outdated and are illegal due to the potential of untreated wastewater overflowing into the groundwater. The Cesspool could have a second tank that is meant to act as an overflow tank and hold the sewage, but it still is just a holding tank and needs to be pumped regularly.

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What is the Difference Between How Septic Tank Systems and Cesspools Function?

While both Septic Tank and Cesspools are designed as onsite waste disposal systems the function quite differently.

How a Cesspool Functions

A cesspool is meant to capture and hold the sewage and wastewater from your home. But it doesn’t process or treat the waste in any way. Water from a cesspool is dangerous and if it contaminates the soil it could make people and animals very sick. This means that the maintenance of a cesspool needs to be done at a far greater interval than that of a septic tank.

How a Septic Tank System Functions

Let’s consider how cesspool functions (described above) versus how a septic tank system functions. A septic tank system is designed with various components besides the septic tank itself.

Once the sewage leaves your house and enters the septic tank via the inlet pipe the tank is designed and sized to be able to hold the waste for 24hours while bacteria process and treat the solid waste.  The solid waste or scum layer at the top is broken down by the bacteria in the tank.

As the bacteria process the solid waste they turn it into liquid.  The liquid sits between the scum layer and the sludge at the bottom of the septic tank. The treated water then moves through a baffle out of the septic tank and into an absorption area like a leach field. While it moves through the system into the leach field it is being filtered by layers of sand and gravel.

The main difference between how a septic tank and cesspool function is that a septic tank system is meant to process and treat the wastewater before releasing it back into the environment, whereas a cesspool does not treat the wastewater and any overflow or absorption of the sewage into the surrounding soil or water table is dangerous.

What is the Difference in Maintenance Requirements for a Septic Tank and Cesspool?

As you can see from the first part of our article, the design and function of a septic tank and cesspool are quite different, and thus logically it makes sense that the maintenance requirements for each also be different.

Let’s be very clear both systems need to be maintained properly to ensure you maximize the life of the system and keep them working properly.  Basic maintenance can save you a lot of headaches and far greater costs down the line, so it is best practice to make sure you are tracking and maintaining your system at the right intervals based on usage and the size of your system. If you want help spotting if your septic tank is full read this, or if you need to schedule septic tank service from a local expert.

With that being said, what is the proper maintenance schedule for your septic tank versus a cesspool? A septic tank is designed based on the size of the home and expected number of users in that home. Depending on the usage your septic tank system gets it should be pumped every 2-3 years. If you need your septic tank pumped click here for local service.

A Cesspool is designed to hold the wastewater and thus should be pumped depending on the amount of usage it gets, this can be on a monthly, quarterly, or annual intervals.

What is the difference in cost between a Cesspool and Septic Tank?

Much like everything else, the cost of installing a cesspool or septic tank will vary depending on where you live.  But to get a general idea on how the cost compares, in general, a septic tank system will cost at least $2000 more than a cesspool. The best rule of thumb is to expect higher costs with a septic system installation.

Remember septic tank systems treat the water before it goes back into the environment and many local cities have made cesspools outdated and illegal, so as they fail you may be required to upgrade to a septic tank system. A new septic tank system that is well maintained should last about 40-50 years.

Some towns like Suffolk County in Long Island, NY are purposing legislation to require failing cesspools to be replaced with a septic tank system due to the possibility of contamination. You can read more about this proposal here.

The best thing to do before you decide on how to proceed when it comes to installing a new septic tank or cesspool at your home is to make sure you check with local authorities and see what the guidelines are around both.  Make sure that you understand how these systems work prior to purchasing an older home, so you can make sure to do your due diligence before making a decision.

When my wife and I purchased our home, we had a full inspection and a separate septic tank inspection. Good thing we did, the home we purchased had a failing septic system. We made sure to negotiate that in the price of the home, as it cost about $24,000 to replace, which wouldn’t have been fun right after purchasing a home.

If you need to get your septic system serviced find a local professional in our state by state directory. Simply click your state below.