How to Construct a Small Septic System (with Pictures)

Factors in Calculating Septic Tank Cost

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From house size to soil makeup, several factors influence septic tank costs. These costs also vary by region where soil content, permits, and material fees vary from one state to the next. While the national average for installing a septic tank is $6,361, the high end cost to install a septic tank system is $18,650. The following list includes the main factors that can affect septic tank installation so you can have a better idea of how to answer the question: How much does a septic tank cost?

House Size

House size is a primary factor in considering what size septic tank to purchase since it must be able to handle the amount of water and waste being produced. A 3-bedroom home would need a 1,000 gallon tank, which costs on average $600 to $1,000.

Tank Gallon Size

Standard septic tanks start at 750 gallons for 1- and 2-bedroom homes. A 3,000-gallon tank can accommodate the needs of some buildings with more than approximately 15 occupants, which would cost between $2,900 and $3,900.

Anaerobic vs. Aerobic

Anaerobic systems are less expensive septic tanks that can be installed (costing $2,000 to $5,000). They rely on oxygen-averse bacteria to naturally break down waste in the tank. Aerobic systems can cost between $10,000 and $20,000 to install since they utilize an air pump to aerate the tank to let oxygen-loving bacteria break down the waste.

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Mound Septic System

When a ground inspection reveals that the soil is not well suited for a septic tank drain field, homeowners can install perforated drain tiles and a thin biofilm that help provide a suitable environment to naturally purify wastewater before it reaches the water table below. Building this space below the septic tank can result in a mounded appearance and can cost $15,000 to install on average.

Sand Filter Septic System

A sand filter septic system uses a pump to push the liquid or effluent matter to the filtration system, which consists of a box filled with sand-filled pipes. The wastewater is naturally filtered through the sand before reaching the water table below. On average, these septic tanks cost between $6,000 and $10,000 to install.

Pressure Distribution Septic System

For an average cost of $7,000 to $10,000, homeowners could opt for a pressure distribution septic system that can be installed within 2 feet of the water table. It utilizes pumps to process the effluent liquid into the drain field more quickly for processing before reaching the water table.

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Video

Septic Tank Cost: DIY vs. Hiring a Professional

Installing a septic tank system is no small task, but when municipal sewer systems are unavailable, it’s a task that’s perhaps unavoidable. While the costs to install a septic tank may seem high or complicated, it’s often a more cost-effective option to install a septic tank than trying to install sewer lines from the city, if that’s even an option.

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Many homeowners are interested in doing a DIY septic tank installation to save money. There are a number of tasks that can easily be accomplished by homeowners. Coordinating soil tests and obtaining proper permits are easy tasks. Homeowners can also remove existing landscaping features or dig the holes and trenches for the septic tank. Beyond these steps, it’s best to consider leaving the actual installation to a professional company that is licensed and insured in order to complete the job safely.

The stakes are high when installing a septic tank system since it’s the method of collecting and purifying infectious disease waste like E. coli. Improperly installing a septic tank could result in foul smells, contaminated water sources, and standing water on the property, all of which can put family and neighbors at risk. With qualified professionals doing the heavy lifting, homeowners can enjoy a smooth system that requires little effort to maintain. Once a septic tank company has been selected, homeowners can work with them to identify any tasks that can be done by the homeowner, if desired.

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Cost to Install A Septic System for an RV

If you’re building a more permanent septic system for your RV, then prices are the same as installing one for a house at $3,300 and $5,000. An RV these days is generally understood to be a mobile vehicle. The septic system in an RV consists of a black water or wastewater tank, the contents of which are dumped into a sewer connection or dump station. It will need to be flushed, cleaned, and sanitized regularly to stay in good working order.

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What If I Need to Replace My Septic System?

How much does a septic tank system cost to replace? Your septic system replacement cost depends on the status of your current septic system. If things need to be removed to put in the new system, there can be additional costs with that.

Be sure to ask your plumber about the costs of replacing your septic tank and system compared to the costs of the repairs that need to be done. It might wind up being cheaper to put in a new septic tank system in the long run instead of just repairing pieces one or two things at a time.

Depending on the type of septic tank you choose, it can affect your septic tank system cost. If you’re looking into a septic tank replacement instead of a brand new system, now is the time to change the type of septic tank you have if you need to.

If you’re replacing your septic system due to unexpected damage, your homeowner’s insurance may cover part of your costs. Being able to show regular maintenance on your septic system is an important part of having a claim like this paid.

Septic System Accessory Costs

There are a few additional pieces of your septic system that may need replacement or repair over time. At The Original Plumber, we can help Atlanta area homeowners determine if they need to have their entire system repaired or replaced, or if just a few parts need some assistance. These include:

Septic Tank Baffles

A septic tank baffle protects your inlet or outlet pipes from scum buildup. A baffle costs around $200-$600 on average to replace.

Tank Covers

Your tank cover is made from concrete. These can get damaged with time, especially in the event of inclement weather. These are only a few hundred dollars to replace.

Concrete Distribution Boxes

The distribution box is also known as a D-box. These are made from concrete and are smaller tanks that help move the flow of liquid. These bring the liquids from your septic system out into your drain field. These can cost, on average, anywhere from $500-$1,500.

Septic System Pumps

We may find that you need your pump replaced in order to get your septic system working again. These typically need to be replaced every decade or so. They can cost anywhere from $1,000 to $2,000 depending on your tank.

What Kinds of Septic Tanks are There?

Just like there are different types of septic systems, there are also different kinds of septic tanks. Septic tank types include:

  • Plastic tanks
  • Concrete tanks
  • Fiberglass tanks
  • Steel tanks

The type of material you choose can affect your septic tank cost. For example, a concrete septic tank might be more expensive than plastic septic tanks, but one may better meet the needs of your septic system.

A plastic septic tank may crack and you’d need to replace it sooner than a concrete tank. Concrete septic tanks are some of the most common types of septic tanks because they’re sturdy and last a very long time.

Each of these septic tanks has its own pros and cons, so it’s important to talk to your plumbing professional to see which one will work best for your property, needs, and budget. They can all affect the cost of septic system installation and septic system costs.

Septic Tank Replacement Costs

If you take care of regular maintenance, you won’t need to think about replacing your treatment system for many years. Most tanks store three years’ worth of a home’s wastewater before they are due to be emptied/pumped. Septic tank pumping costs an average of $370 every three years or about $0.25/gallon.

 Septic Tank Replacement Costs   Replacement Item

Septic Tank Replacement Costs
Replacement Item Average Cost
Drain Field Replacement $3,500 – $11,000
Tank Pump Replacement $500 – $1,200
Tank Removal $5,500
Tank Baffle Replacement $23 – $44
Tank Lid Replacement $30 – $65
Tank Filter Replacement $230 – $280

Septic Drain Field Replacement Cost

Septic Drain Field Replacement Cost

Septic drain or leach field replacement will cost between $3,500 to $11,000 with most homeowners paying a total of $7,000 on average. It will cost about $30 per linear foot to dig up the old leach field and $9 to $12 per linear foot to lay the new filtration materials or leach field. A drain field will flood if it gets overloaded with too much liquid, causing sewage to back up in toilets and sinks.

Septic Tank Pump Replacement Cost

When your septic pump goes out, it will generally cost between $500 and $1,200 to replace. A pump is required to bring effluent up to the drain field. The pump is an essential piece due to the fact you need to pump your system every 2 to 3 years for about $370.

Septic Tank Removal Cost

Septic tank removal includes emptying the tank first and then removing or replacing it. Pumping the tank will cost about $250 to $600, depending on local labor costs, tank size, how far you are from a dumping ground, and dump fees. Removing and replacing a 1,000-gallon concrete tank will cost approx. $5,500.

Septic Tank Baffle Replacement Cost

It will cost $23 to $44 for the septic tank baffle part—this directs wastewater through the septic tank properly without disturbing the natural settling of the tanks’ scum layer.

Septic Tank Lid Replacement Cost

Metal tank lids will typically rust over time, and concrete covers can crack and will need to be replaced. A septic tank lid costs about $30 to $65 to replace not including professional installation.

Septic Tank Filter Replacement

Septic Tank Filter Replacement

The most common repair you will perform on your septic system is filter replacement. Expect to pay around $230 to $280 to install a quality filter for your septic tank.

Cost to Install A Septic Riser

Installing a septic tank riser will give you access to your septic tank at ground level by adding a piped shaft from the top of the tank to the ground level. A riser will cost you about $300 to $400 installed—very much worth it to give maintenance crew easy access should it needs repairs or maintenance. A polyethylene riser will be lightweight and easy to remove, while a concrete riser can be cumbersome and difficult to install, and can crack. Newer tanks usually come with the riser already attached, but old tanks can be fitted with one.

  • Septic Tank Riser Installation Cost – Installation or the labor cost to install your riser will be approx. $200. Add that to the price of the riser (below).
  • Plastic Septic Tank Riser Cost – A plastic septic tank riser with an adapter ring and lid costs approx. $75 to $155, with the highest-rated riser kits by Aero-Stream costing $195–$325, available from 7”–51” tall.
  • Concrete Septic Riser Cost – Concrete risers come in varying lengths with square, rectangular, or round holes and walls that are 3”–4” thick. Prices are only available from manufacturers upon request.

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Septic vs Sewer Cost

A septic system costs $3,100 to $9,600 to install while connecting to a main sewer line can be slightly more affordable, around $1,500 to $8,000. Think of this system as your own personal sewage system. A septic system treats wastewater on site, with an underground tank and pipe system on your property. If your home plumbing system is not hooked up to a septic system, it is connected to the main city sewer line. Sewage connections carry the wastewater from your home and route it underground to a city or county treatment plant.

SystemCost (Installed)Sewer$1,500 - $8,000Septic$3

SystemCost (Installed)
Sewer$1,500 – $8,000
Septic$3,100 – $9,600

Septic Tank Systems and Materials

The price of your new septic system is based on the size of your home, including the number of bedrooms, the type of system selected, and your septic tank’s material. Below is a list of various treatment systems and tanks available and the standard prices.

Conventional Septic System

A conventional septic system uses gravity to move household sewage into the septic tank. Sewage is separated into layers, with solid waste settling at the bottom and liquid sewage rising to the top.

When liquid sewage rises to the level of the outflow pipe, the liquid waste flows into the drain field, where it decomposes further. These conventional septic systems are usually the most affordable, with an average cost around $2,000 to $7,000.

Anaerobic Septic System

The anaerobic septic system uses anaerobic bacteria to break down waste in the septic tank. These systems don’t require additional chemicals or power. They serve as an affordable option for homeowners.

However, anaerobic systems are not effective at cleaning the tank and require a larger drain field to work correctly. The added size increases the average cost to $3,000 to $8,000.

Alternative Septic System

An alternative septic system collects sewage in the same way as a conventional system, but it breaks down the sewage in the tank using oxygen instead of naturally occurring bacteria. Drain fields for alternative systems generally need less land and release cleaner wastewater. However, this benefit comes at an increase in cost, with systems usually priced around $4,000 to $15,000.

The following types of alternative septic systems are available for homeowners:

  • Chambered septic system: Replacing the need for a gravel/stone system, chambered systems use gravelless drain fields with leaching chambers for the filtration. They are ideal in areas with high groundwater tables or limited gravel.
  • Constructed wetland septic system: Similar to the natural process that occurs in real wetlands, this system cleanses wastewater using bacteria, microbes, and plants. The waste then helps those plants to thrive. This design is the most eco-friendly septic system available.
  • Drip septic system: Drip systems are made to “irrigate” septic water over a larger area using long tubing throughout the leach field.
  • Evapotranspiration septic system: These systems use a large open-air tank to allow the effluent to evaporate naturally. This type of system works best in climates that receive abundant sunlight and heat.
  • Pressurized septic system: This system focuses on using pressure to distribute effluent evenly. It can be paired with other septic systems that focus on water treatment.

Engineered Septic System

Engineered septic systems are the most complex and are generally needed due to poor soil or the home being situated on an uphill slope. Just like alternative and conventional septic systems, engineered systems collect and separate waste in a tank. Instead of relying on gravity to drain, the liquid waste needs to be pumped into the leach field to distribute throughout the land evenly. These systems generally cost $7,000 to $20,000.

Below are some examples of engineered septic systems:

  • Mound septic system: Mound systems employ mounds of sand to clean the wastewater instead of a typical leaching field.
  • Aerobic system: By pumping oxygen into the treatment tank, these systems generate naturally occurring bacteria to process the waste.
  • Recirculating sand filter system: This septic system uses sand to filter effluent out after leaving the pump tank. The treated water then flows to the drain field. This sand filter septic system works best in areas near bodies of water or with a high water table.

Septic Tank Materials

Several different materials can be used for your septic tank.

Here are the most common types available for your home: 

  • Concrete: Concrete tanks are durable and rust-proof but are hard to repair if damaged. Depending on the size, concrete tanks can cost up to $2,000.
  • Plastic: Plastic septic tanks are cost-effective but prone to damage. They cost around $1,200.
  • Fiberglass: Fiberglass tanks are stronger than their plastic counterparts but can be shifted or displaced if the water table rises too high. These tanks can cost up to $2,000.
  • Steel: Although steel is considered a durable material, steel tanks are not used in newer installations since they are prone to rust over time. These tanks are usually found in older installations and should be replaced with a newer option when they begin to deteriorate.

Conclusion

A new septic tank or septic system, either for new construction or an existing property, will always cost at least a few thousand dollars. The national average cost of professional installation is about $5,828, with a typical range of $3,138 to $8,518

The overall cost of the project depends on the type of septic system you use, the size of your home, and any additional services you may need to complete the installation. Though the typical price range is a good set of guidelines, keep in mind that you could end up paying as little as $1,013 or as much as $18,163

Most importantly: DON’T attempt to install your own septic tank unless you’re a professional plumber or other specialist experienced with septic systems. No matter how handy you are, no matter how much money you think you’ll save, the risk of DIY in this case isn’t worth it. 

Main Photo Credit: Andy Rogers / Flickr / CC BY-SA 2.0

Jordan Ardoin is a writer and indoor plant enthusiast hailing from Florida. In her spare time, she enjoys chasing her two cats around the house and trying to keep her houseplants alive.

Septic Tank Materials

Another factor influencing cost is what your septic tank is made from. Here are some of the most common materials:

Concrete

Concrete tanks are the most common type of septic tank because they’re durable. Properly maintained, they can last 20 to 30 years. However, concrete may crack over time. Reinforcing the concrete with rebar helps increase its strength under pressure. Installation is more challenging, and extensive equipment is needed because of its weight. The cost for an average-sized concrete tank is $720 to $2,050.

Fiberglass

Fiberglass doesn’t weaken when used underground, and it’s nonporous, so it won’t attract algae growth. Installation is easier because the tank is light. Unlike concrete, it won’t expand or contract, so you don’t have to worry about cracking. The average fiberglass tank costs $1,600 to $2,000.

Plastic

Plastic tanks are light and easy to install. They’re also quite durable. Depending on the type, plastic tanks cost $830 to $1,400 on average.

Steel

Despite steel’s strength and durability, septic tanks made of steel can rust can collapse if not properly cleaned. As a result, some local authorities have increased regulations to discourage their use. You’ll usually find them in areas where the system already existed. If you can get one installed, they cost $900 to $9,900.

Site Preparation Costs

Since the above costs were just for the system itself and not the site preparation, you’ll want to know how preparation will influence your total septic tank cost. The amount of digging the crew will have to do will influence the price. It can impact your low-maintenance landscaping, and you may find yourself updating, replacing, or repairing it after they finish the installation process. 

The number of plants and shrubs the crew has to remove will influence your excavation costs, how hard the soil is, the type of machinery they’ll need for the project, and the terrain’s quality also play roles. On average, excavation will influence your septic tank cost by increasing it between $1,000 and $4,500. Most companies will add site preparation costs into the total installation prices. This way, you may end up getting a lower rate overall for the excavation process. 

What is a Septic System, and How Does it Work?

A septic system is an underground wastewater treatment structure most often used when a municipal sewer system is not available. They are commonly found in rural areas rather than cities.

A typical septic system consists of a septic tank, a distribution box, and a leach field. A leach field is also called a drain field or soil absorption field. A septic tank will help digest organic matter and separates floatable matter such as grease, oils, and solids from the wastewater.

The system discharges the liquid from the septic tanks into perforated pipes buried in a leech field, designed to release the effluent into the soil slowly.

Although the first septic tanks have been in use since the late 1800s, they did not become popular until the 1960s. Up until that time, a cesspool was common in most homes.

Cost Factors to Install a Septic System

Cost considerations, in addition to the size and type of system you choose, also include:

  • Engineering — Septic systems require the input of an engineer at an average of $500–$650. Factors they consider when designing your system include:
  • Slope — conventional septic systems can’t be installed where land slopes more than 30 degrees.
  • Fill — native soil is required. The use of engineered fill may be prohibited or require a special permit.
  • Wetlands — drain fields can’t be designed to discharge into wetlands or waterways.
  • Drainage — how well your soil absorbs water — determined by soil testing — as well as external forces that could flood your system.

Plans for new systems cost the most and take up to three weeks to complete. You’ll pay a little less when replacing an existing system.

Soil Testing

To determine which type of septic system you need, engineers first do percolation, or perc, tests that show how well your soil absorbs liquid. New home sites may fail if it isn’t permeable enough to absorb discharge or if it’s so porous that water runs right through it before it’s adequately filtered.

Typical perc testing requires drilling two holes that simulate conditions for a septic system. It takes up to a day to do at an average price of $300–$1200. Costs depend on the complexity of the procedure based on local regulations.

So-called “deep hole” soil tests look at soil down to a depth of 10 feet to ensure there are no barriers to drainage such as rock or a high water table. Prices range from $900–$2000.

Permits and Inspections

Permits for septic tanks range from $50–$200. Most towns also require a post-installation inspection at the cost of $100–$200.

Land Clearing

An open area is required for both tank and drain field installation. For areas of a quarter-acre or less, expect to pay $800–$100 for light cleaning, including small tree and stump removal. Restoring your landscape to its original condition after installation adds $300–$600.

Septic System Upgrades

Upgrades to your septic system like these can make it more user- friendly:

  • Septic Tank Riser

Cleaning an underground septic tank requires digging a hole in your lawn unless it’s equipped with a riser. Risers are plastic or concrete extensions that sit atop the tank and offer easy access to the pumping port.

Not everyone wants a riser on their lawn — they’re not pretty — but they come highly recommended if you live in a harsh climate or hate the work of restoring sod after your tank is cleaned. Costs range from $70–$350 installed.

  • Tank Alarms

Select types of septic systems can be equipped with tank alarms. They work like floats in a toilet tank and can tell you if water has reached an unsafe level because of a blockage, allow you to alter your usage until the situation is corrected. Prices range from $85–$230 installed.

  • Lift Stations

If a septic tank is installed below the level of the drain field, a lift station can keep effluent flowing when gravity fails. Lift stations are pumps that kick in when water in the tank reaches a preset level. Installed, they add $2500–$5000 to the price of a system.

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