Septic tank service costs depend on your project and location. Check with a local pro for your specific job.
Small septic system installation costs between $2,910 and $18,600, and your tank and leach field size drive totals.
Your soil type and tank material choice affect excavation needs, drain field design, and overall installation complexity.
You should budget for perc testing, excavation, and permits, which add $1,350 to $5,100 to your project.
Hiring a local septic tank company ensures proper sizing and placement, preventing contamination, backups, and slow drains.
A small septic system costs between $2,910 and $18,600, with an average of $4,100 for a smaller system.
Whether you’re setting up a garage apartment or even a cottage off the grid, a septic system certainly beats an outhouse. Luckily, smaller systems are available, so you don’t have to pay for more than you need. Depending on your tank size, soil composition, and the type of system you want, costs can vary considerably.
If you’re looking to install a small septic system, the smallest tank size you’re likely to find is 500 gallons. However, many municipalities have strict requirements for septic tank size, and they often require 750 gallons or even 1,000 gallons at minimum. Check with your local regulatory agency or get in contact with a septic pro to make sure your wastewater project abides by local laws.
| Tank Size in Gallons | Household Size | Average Cost With Installation |
|---|---|---|
| 500 | 1 bedroom | $875–$1,150 |
| 750 | 1 to 2 bedrooms | $2,910–$13,900 |
| 1,000 | 2 to 4 bedrooms | $4,030–$18,600 |
Conventional septic systems will require a tank, piping, and a leach (or drain) field. You’ll also need to factor in excavation, soil testing, and building permits.
Below is a breakdown of what you might pay.
The tank itself will run you between $500 and $1,500 based on its size and type. As mentioned earlier, some places require a minimum of 750 or 1,000 gallons, so be sure to check local laws. Here are some general ranges by size.
| Septic Tank Size in Gallons | Average Cost for Tank Only |
|---|---|
| 500 | $500–$900 |
| 750 | $750–$1,200 |
| 1,000 | $900–$1,500 |
After wastewater gets separated and treated in the septic tank, it runs to a leach field. Here, it drains through soil, sand, and gravel, getting cleansed naturally before reaching the water table.
Depending on the type and size of your septic system, as well as your soil composition, leach field costs will vary significantly. On average, you can expect to pay $1,000 to $5,000 for leach field installation, with a field for smaller tanks costing on the lower end of that range.
Excavation costs should be included as part of your quote. You’re likely to pay anywhere from $200 to $1,800 for excavation. Tanks that are closer to 500 gallons need less land excavated, therefore decreasing the overall cost for this task.
A perc test will cost between $750 and $1,300. This test will determine the ground’s capabilities when it comes to absorbing and filtering water. For new installs, as well as repairs, you’ll need to show proof of this assessment.
Most places will require a building permit fee, ranging from $400 to $2,000. Costs will vary based on regulations in your area.
There are three main types of septic tanks: concrete, plastic, and fiberglass. Concrete is a common choice that can last a couple of decades, though it is vulnerable to cracking and separation. Plastic and fiberglass are more durable, but they are also more susceptible to damage during installation. Below are some general cost ranges to consider for each.
| Material | 750-Gallon Average Cost | 1,000-Gallon Average Cost |
|---|---|---|
| Concrete | $2,860–$13,900 | $3,830–$18,600 |
| Plastic | $2,660–$13,900 | $3,630–$18,600 |
| Fiberglass | $3,360–$13,900 | $4,330–$18,300 |
If you’re still unsure on which material to go with, below are pros and cons across concrete, plastic, and fiberglass.
| Concrete | Plastic (PVC) | Fiberglass |
|---|---|---|
| Long-lasting (up to 40 years) | Long-lasting (up to 50 years) | Mid-range life span (20 to 30 years) |
| Approved for use in every state | Budget-friendly | Least costly |
| Not easily damaged | Lightweight | Stronger than plastic |
| Less prone to rust | Less prone to cracking | Won’t rust |
| More costly | Easy to damage during install | May shift depending on soil conditions |
Traditional septic systems feature either an anaerobic or aerobic setup. Anaerobic systems are the most common, though aerobic septic systems are much more efficient (and costly).
A small anaerobic septic system can cost you between $3,000 to $8,000. This system relies on anaerobic bacteria, which are bacteria that don’t use oxygen. These bacteria work to break down waste within the septic tank before it gets further processed in the soil.
An aerobic septic system can cost anywhere from $10,000 to $18,600. These systems use oxygen-loving aerobic bacteria to break down waste more effectively. While this system calls for a higher budget, it breaks down waste in the tank more efficiently, saving you in leach field expenses.
Your septic system’s leach field has the biggest impact on overall cost, as prices vary considerably based on the size needed and the type of soil you have. Here’s a list of all the factors that might impact your small septic system cost:
Soil composition
The size and type of septic tank
The size of the leach field
Excavation and other labor costs in your area
Obtaining necessary building permits
Large or small, a septic system must be the right size and in the right place according to your property’s soil type, groundwater conditions, and local health code. No one wants the backups, slow drainage, or contamination that faulty septic tanks can cause. Choosing a local septic tank company that understands these challenges and your area’s environmental and regulatory factors can ensure you get a system that functions reliably now and in the future.
Septic system installations are complicated, so trust a pro for these reasons:
Small septic systems require soil testing, trench layout, and a precise connection to your home’s plumbing. A pro can get it right and provide warranties for peace of mind.
Septic tank pros understand how to size septic systems based on household water use, soil type, and drain field capacity.
Septic installers have the experience and tools to conduct or coordinate percolation tests, ensuring your soil can properly absorb and filter wastewater.
Pros handle permitting and ensure septic system layouts meet local health department and environmental regulations.
Excavation isn’t easy—pros know how to excavate safely and position the tank and drain field to prevent leaks, backups, odors, drain field saturation, and contamination.
Having a properly and professionally installed septic system will help your home pass inspections and can increase your home’s value.
Discuss the number of people in your home and their average water use habits, as these will determine the tank size.
Ask if your soil conditions are suitable for a traditional drain field or if an alternative system is necessary.
Review where your septic contractor will install the system, and confirm whether it’s easy to access for future maintenance and pumping.
Learn how installation will impact the layout of your yard, driveway, gardens, trees, and other features.
Ask if your septic tank pro recommends adding risers, inspection ports, or other features to make maintenance easier.
Home is the most important place on earth, which is why Angi has helped more than 150 million homeowners transform their houses into homes they adore. To help homeowners with their next project, Angi provides readers with the most accurate cost data and upholds strict editorial standards. We extensively research project costs to develop the pricing data you see, so you can make the best decisions for you and your home. We rely on reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects.
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