How Much Does a Septic Tank Cost to Install?

Written By Arnold Long
Updated On

Are you wondering how septic tanks work or how much it costs to install one?

You’ve come to the right place!

In this Mr. Blue Plumbing guide, you’ll learn:

  • Can you install a septic tank yourself?
  • What are the different kinds of septic tanks?
  • When should you have a plumber replace it for you?
  • What does septic tank installation cost?

And much more!

How Much To Install A Septic Tank?

So, if you’re looking for information on septic tank installation, or you want a cost guide for the plumbing service, keep reading our detailed guide below to get answers to all of your questions!

What Is a Septic Tank?

A septic tank is an integral part of a septic system, which is designed to receive waste from your plumbing fixtures and dispose of it safely. All homes are fitted with some type of waste disposal system; some are connected to a public sewer system, some drain to a cesspool, and others move waste into a septic tank. A septic tank is a container, typically made of fiberglass, steel, or cement, that collects and treats waste from your home.

All of your fixtures drain to your main waste line, including toilets, bathroom sinks, kitchen sinks, dishwashers, washing machines, and bathtubs. If you have a septic system in your yard, any wastewater or human waste leaving your home through the sewer line enters your septic tank for treatment and disposal.

What Do You Need To Know About Installing a Septic Tank?

Installing a septic tank is a convoluted and potentially dangerous process that should always be done by a professional. However, knowing how septic tanks work, why and when they should be installed, why they need to be pumped, and why the installation process is so challenging will help you understand the system and choose the best professional to install and service yours.

How Does a Septic Tank Work?

A septic tank is a large container that is typically buried in the front or rear yard of your property. The fixtures in your home move waste to drainpipes and eventually to your main sewer line. This waste line exits your house and leads directly into your septic tank in the yard.

The waste flows down into the tank via an inlet valve, which prevents waste from backing up into your home. The waste drops into the septic tank and naturally separates into three layers. Grease, oil, and soap fat from cooking and bathing naturally float to the top and develop into the scum layer.

Liquid waste, including greywater and urine, remain in the middle of the tank. Solid waste, including toilet paper and fecal matter, fall out of the liquid and drop to the bottom.

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The tank contains a large number of bacteria that feed on solid human waste and help treat liquid waste to make it safe for disposal. As the container fills, a tank pump moves the liquid waste – called effluent – through an effluent filter, up a protective baffle, and out of the tank via an outlet valve, which again prevents sewage backup into your home.

Once the treated liquid waste exits the tank, it typically travels to an area of your property where it can be safely disposed of. The waste is dispersed evenly via a distribution box to several different areas for disposal within the septic drain field, also called the leach field.

Each drainpipe that is a part of the leach field is made of perforated pipe surrounded by gravel or crushed rock.

Bacteria thrive all along the drainpipes as well as in the material around them, so the sewage is continuously treated as it flows through your septic system. Eventually, cleaned water empties into the soil.

Most modern septic tanks have three access risers that allow a professional to access the interior through a tank lid. These risers are typically located in the middle of the tank for effective sludge removal and over the inlet and outlet valves for easy cleaning and clog clearing.

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Why Do Septic Tanks Need to Be Installed or Replaced?

All homes need a means of safely disposing of waste and greywater. The three options are public sewer systems, septic systems, and cesspools. If you live in a rural area where connection to a public system isn’t possible, installing a septic tank is an excellent option for waste treatment.

Additionally, you may want to have a septic tank installed if you currently have a cesspool that is giving you problems. Cesspools are similar to septic systems, but instead of using pumps to move waste after it has been treated, cesspools are designed to drain continuously. Cesspools are more prone to clogs and issues with backed-up sewage, so ongoing problems with your cesspool might be solved by replacing it with a septic system.

If you already have a septic system installed, you’ll want to replace the tank if any of the equipment malfunctions or causes ongoing problems. Many homeowners have issues with sludge build-up in the bottom of their tank, which could be caused by insufficient bacteria or a tank that is too small for the size of their home and the number of family members.

Clogs in your system can sometimes be cleared, but they may damage the tank or valves and require replacement.

Septic tanks generally last for several decades before needing replacement. However, if yours gets damaged for any reason from construction, natural disasters, or invasive tree roots, you’ll need to replace the tank quickly before your soil becomes too contaminated with untreated waste.

When Do Septic Tanks Need to Be Replaced?

Septic tanks typically have a 40-year lifespan, after which they need to be replaced. If your tank is nearing that age or you’re not sure when the tank was installed, you should consider replacing it before it presents a significant and costly problem.

Any malfunction of your septic system can be extremely dangerous, so you should replace your tank if you ever notice issues with sewage treatment, leaking, or soil contamination.

A soil test for sewage contamination or high nitrate or nitrite levels in water sources typically means that your septic tank is leaking untreated sewage into the ground.

Similarly, coliform bacteria in water sources like ponds or wells on your property is very hazardous and suggests that your septic tank needs immediate replacement.

Some homeowners find standing water in their yard that isn’t linked to excessive rainfall or flood. If the ground above or around your septic tank is unusually soggy or has water pooled on top, this is a clear indication that the tank is leaking.

Any backup of water or sewage in your yard typically means your septic tank should be replaced right away.

Septic tanks come in various sizes and are installed to match your home size and the expected demand placed on the system. If you expand your home or your family grows in numbers, it might be a good idea to replace your current septic tank with a larger model to accommodate the added stress placed on the system.

Your septic system may become clogged for a variety of reasons, including an expanding family or home and disposal of problematic material like dental floss, sanitary napkins, cotton balls, cotton swabs, or other material that won’t break down in your tank. Septic tanks can also simply become clogged over time with proper use if they aren’t pumped regularly.

A clog in your septic system can cause sewage backup and property damage that puts your family at risk of illness and can potentially cost thousands of dollars in repairs. As such, any signs of a clog or backup should be corrected immediately and may require septic tank replacement.

Many homeowners find slowly draining plumbing fixtures throughout their homes if their septic tank is backed up or clogged.

Can You Install a Septic Tank Yourself?

Installing a septic tank is a very convoluted process that involves significant soil excavation, proper connections between your main sewer line and the tank as well as the tank and the distribution box, and careful backfilling to prevent tank damage.

In addition to how challenging the work is, everything needs to be done safely, with a building permit, and in accordance with local building code and Environmental Protection Agency (EPA) regulations.

As such, installing a septic tank should never be done as a DIY home improvement project. Far too many things can go wrong with the installation that can lead to hazardous soil contamination, sewage backup, severe property damage, and damage to your septic system equipment that can total thousands of dollars. You should always leave septic system installation or replacement to a professional.

Why Do Septic Tanks Need to Be Pumped?

Septic tanks can last for a long time if they are properly maintained, and a crucial part of the maintenance process is carrying out routine pumping. As you use the plumbing fixtures in your home, the scum and solid waste layers within your septic tank grow. The bacteria in the tank feed on the solid waste layer, but some sludge typically forms at the bottom of the tank.

If the scum layer on top gets too thick, it will begin to move through the disposal valve, clogging the filter and the dispersal pipes. This can result in very severe damage to your leach field and necessitate an entire septic system replacement.

If the solid waste layer or the sludge gets too thick, it too will move through the disposal valve, causing costly clogs and potentially flooding your yard with untreated sewage. A cleanup of your yard and the drainpipes can be very costly and dangerous.

The best way to prevent your septic system from backing up or getting clogged is to carry out regular septic tank pumping. The service includes the removal of the top layer of scum that would otherwise continue to build up, excess solid human waste, and any material that made its way down into your septic tank that could cause clogs.

How Often Do Septic Tanks Need to Be Pumped?

The scum and solid waste layers in your septic tank can accumulate quite quickly, so septic pumping is recommended every three to five years. You should also schedule a pumping service if you notice your fixtures draining slowly or any other signs of a backup, clog, or other septic tank problems.

How Do You Install a Septic Tank?

Before we describe the process, it’s imperative you understand that septic tank installation or replacement should only ever be attempted by a certified plumber or septic tank specialist.

Septic systems should never be accessed or worked on by homeowners, even if they have extensive DIY experience. Simply opening your septic tank can release toxic gases into the air that can lead to death, so never attempt to open, replace, or maintain your septic system yourself.

To install or replace a septic tank, a professional will begin by excavating the soil in your yard where the tank will be placed. Placement generally depends on where your main waste line exits your home, as it will need to lead into the tank. The installer will then typically use heavy machinery to lower the tank into the ground safely. Once situated and level, the plumber can connect the tank to your waste line using an inlet valve.

If your septic system expert is replacing an old septic tank, they will simply connect the tank to the existing leach field using an outlet valve, seal the tank, and backfill around the unit. If you’re installing a septic system where one didn’t previously exist, or you’re replacing a cesspool with a septic tank, your installer will continue by excavating for your leach field.

Check out the video below to see how septic tanks are installed:

What Are the Different Kinds of Septic Systems?

There are many different types of septic systems, each with a different way of treating and disposing of waste. We’ll discuss the styles below and offer some insight into how they function differently.

Traditional Septic System

A conventional septic system – also called an anaerobic septic system – is the one we’ve chosen to describe above, as they are the most common throughout the United States. In this type of system, the waste from your home travels through the main waste line and into the septic tank. A pump is used to move the liquid waste from the middle of the tank to the distribution box.

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The distribution box evenly distributes waste to the branches of your drain field. The drainpipes leach cleaned water into the soil, where treatment continues by bacteria in the ground.

Chamber Septic System

A chamber system works very similarly to a traditional septic system, but the pipes that distribute cleaned water to the soil are significantly broader and act as treatment chambers rather than just as a method of dispersal.

Like a conventional system, wastewater enters your septic tank via the waste line and is treated by the bacteria within the container. Liquid waste is pumped to the distribution box, which then distributes waste to large chambers under the ground. These chambers are often made of wider plastic piping and generally don’t use gravel or crushed rock to accept water.

Chamber systems provide greater flow of treated sewage and offer a better solution for waste management in homes that don’t have continuous waste production, such as in summer homes or short-term rental properties.

Drip Distribution System

A drip distribution system ditches the larger dispersal pipes and instead relies on significantly smaller piping that is buried just a foot or so under the earth’s surface. Installation of the leach field for this system is much cheaper than other styles because it requires far less excavation.

However, a drip system requires a more complex distribution box that can disperse waste effectively and adequately to each of the different drip tubes. This box requires more excavation and planning, as well as an electrical connection to run the sophisticated pump.

Aerobic Septic System

An aerobic septic system differs from others, not in the dispersion method but in how the sewage is treated. An air pump forces oxygen into the tank, making the bacteria more active and effective at thoroughly treating the sewage before it’s disposed of into the soil.

These systems are ideal for homes located near public water sources or high water table where contamination is a major concern.

Mound System

A mound septic system disperses waste over a large mound of underground gravel and sand. The drain field for these systems can be significantly smaller and set at shallower depths than those in a conventional system, so they’re ideal for properties with shallow bedrock or high groundwater. The sewage is primarily treated by bacteria residing in the sand beneath the drain field.

Recirculating Sand Filter System

In a recirculating sand filter septic system, effluent from your septic tank is pumped into a separate treatment chamber filled with sand and additional bacteria. The second tank acts as a second round of filtration and treatment before the waste is moved to the drain field. This type of system is ideal for properties near high groundwater or public sources of water where contamination is a severe issue.

Evapotranspiration System

An evapotranspiration septic system lacks a drain field and never distributes effluent into the soil. Instead, it includes an open-air tank after your septic tank, where the effluent evaporates into the air. These systems are ideal in areas where ground contamination is a significant concern, but they’re only suitable in dry climates where evaporation can occur readily.

Wetland System

A relatively uncommon type of septic system, a wetland setup uses a man-made wetland to treat sewage naturally using plants and bacteria that use the chemicals found in wastewater.

The wetland is constructed over an underground tank situated beyond your standard septic tank. Treated waste is eventually pumped into the soil via a leach field, where additional treatment occurs.

When Should You Hire A Professional To Install a Septic Tank?

Whether you’re installing a septic system where one didn’t previously exist, or you’re replacing your cesspool with a septic tank, you should always hire a professional to do the work for you. Septic tanks and cesspools are not only very challenging to unearth and access, but the gases and contents within the containers are hazardous to your health and potentially deadly.

Additionally, any mistakes during the installation of your septic system could easily lead to thousands or even tens of thousands of dollars in property damage and fines from the health department. As such, no homeowner or DIYer should ever attempt to install or replace a septic tank on their own.

How Much Do Plumbers Charge to Install a Septic Tank?

The national average cost to install a new septic tank is around $4,000. This includes the cost of the tank as well as any labor costs required during the process. Depending on the amount of excavation needed, the soil conditions, the style of septic system you’re installing, and the size and number of bedrooms and bathrooms in your home, your total cost can fall anywhere between $3,000 and $15,000.

One of the most significant cost factors for a new septic system will be the style of system you choose. Standard systems are the most affordable, around $3,500, while mound systems can reach the higher end of the cost range of $15,000. Sand filter and aerobic systems typically fall between $8,000 and $10,000.

Regardless of the type of system, the tank size will affect your price significantly. For example, a 1,000-gallon tank for a 3-bedroom home will be significantly cheaper than a larger one for a 5 or 6-bedroom house.

Finally, the tank material you choose will influence the total septic system cost as well. For example, a concrete septic tank can reach up to around $2,000 for the equipment alone, while a PVC or plastic septic tank averages around $1,000.

Keep in mind that these replacement costs don’t include restoring your landscaping to its previous condition, which can add several hundreds of dollars to your total.

What Should You Look For In a Septic Tank Installer?

Above all else, you should always choose an experienced professional to install your septic system. A local contractor may offer to do the work for less money, but you want an expert installation to avoid property damage, sewage backups, and other costly problems down the road.

Some plumbers exclusively work based on an hourly rate, but a professional with experience installing septic tanks should be able to estimate the total installation time and cost of the materials. We recommend choosing a plumber who provides a flat rate, as this will give you a total price upfront and help avoid overspending on a slow installation.

Lastly, we strongly recommend choosing a plumber who offers a satisfaction guarantee or a warranty on the installation. Installing a septic tank is a complicated process, and an expert who promises you’ll be pleased with their work is more likely to do things correctly and safely.

Meet Your Plumbing Expert

Arnold Long

I've been helping folks with plumbing issues ever since I can remember. Some folks may think it's a dirty job, but I love it. MrBluePlumbing is all about helping folks find what they need to make their plumbing problems go away for good.
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