How Much Does an Engineered Septic System Cost? [2025 Data]

Installing an engineered septic system costs between $7,000 and $20,000, with an average project cost of $15,000. Factors like site prep, excavation, and location can cause the final price to creep up to $25,000 in some cases. Explore the different factors that impact the average cost of engineered septic systems below.

Engineered Septic System Cost Breakdown

The cost of engineered septic systems is primarily—50% through 70%—from labor costs.

Labor

When you hire a licensed, insured, and bonded plumber, you’ll pay $45 to $200 per hour in labor cost. When plumbers install an engineered septic system, you’re typically paying for the time it takes to excavate your yard, prep the site, build the drain field, get permits, and install the system. 

However, depending on your contractor or septic tank company, you could pay a flat fee for some or all of those services. Here are the prices you can expect:

• Land prep: $1,600–$8,000

• Excavation: $1,200–$4,500

• Perc test: $750–$1,850

Ask your contractor to provide a line-by-line written estimate to avoid any surprise bills.  

Drain or Leach Field

A drain field, also known as a leach field, is a major component of your entire septic system responsible for dispersing your filtered wastewater into the soil. The cost to build a drain field is $3,000 to $15,000.  

Engineer Fees

When you need an engineered septic system, it’s not a plumber that’ll design your new septic system but a civil engineer or soil scientist. And because they’ll need to design and potentially oversee your system’s design, expect to pay $500 to $1,000 or 5% to 15% of the project’s design budget. 

Material 

Each engineered system will be structured differently to fit your individual septic needs. But the materials commonly used for them include a septic and pump tank and piping. Some systems such as mounds and sand filters also require sand that costs $15 to $20 per cubic yard and gravel that costs $15 to $75 per yard. 

Permit

Installing an engineered septic tank will require a permit to ensure it complies with your local and state building code requirements. The cost of getting a permit is $400 to $2,000; however, the actual cost varies by city and state.

Engineered Septic System Cost Near You

Labor costs play a significant role in how much you’ll spend on an engineered septic system. Because engineered septic systems require a different installation process than conventional ones, you’ll pay more for the time, experience, and skills required for a proper installation. 

So, if you stay in an area where the ground is too permeable, isn’t permeable enough, or your home resides on a hill, it’ll take longer to install with labor fees of  $45 to $200 per hour.

Engineered Septic System Cost by Type

The most common engineered septic systems are mound, recirculating sand filter, and aerobic. Below, we’ll cover the actual cost of these types. 

DIY vs. Hiring a Pro

Installing an engineered septic system is a complex and highly regulated process that requires professional expertise. Local regulations, soil assessments, and specific engineering requirements must be considered. 

Attempting a DIY installation without the necessary knowledge and permits can result in costly mistakes, environmental damage, and legal issues. You should hire a licensed septic tank company near you with experience in designing and installing engineered septic systems to ensure compliance with regulations and the proper functioning of your septic system.

Cost of Common Add-Ons

While the prospect of DIY septic system installation may not be feasible for properties that need engineered septic systems, we still have several cost-saving tips for you to undertake independently. After partnering with a reputable installation company, collaborate with them to pinpoint which of the following tasks you can tackle yourself:

• Soil testing, which costs $1,400 on average

• Obtaining building permits, which costs $50 to $500 for septic systems

• Landscape prep, which starts at $1,200 on average

Ongoing Costs

Managing septic tank maintenance expenses is vital, as it can range from $280 to $550 on average per year and can be over $1,000 for larger systems. To ensure you minimize these costs and keep your septic system running smoothly, consider the following guidelines:

• Annual septic system inspections cost $200 to $250. 

• Bacteria additives cost $40 per year. 

• Septic tank pumping costs between $250 and $550.

• Cleaning and replacing an effluent filter costs $150.

• Installing an effluent filter on an existing system ranges from $275 to $850.

How Angi Gets Its Cost Data

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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