Septic System Installation Cost Guide

Here’s an overview of what you might expect in terms of costs for both installation and replacement of a septic system.

How Much Does an Average Septic Tank System Cost?

Although a septic tank itself might only cost $1,000 to $3,500, the average homeowner can expect to spend anywhere between $10,000 to $25,000 to install a new septic system. However, the exact costs for installing a septic tank system vary based on factors such as location, the size of the septic tank, soil quality, and more. The exact required size of a septic tank depends on how many people occupy the home. For an average home, most septic tanks have a capacity of between 1,000-3,000 gallons. Septic system costs can be split into materials, labor, and installation costs. 

The cost of the septic tank itself is primarily determined by its size and can range from around $700 for a smaller septic tank to over $3,500 for a larger one. Size requirements depend on the size of your home and the number of people living in it. All other things being equal, the larger your home and the more people that live there, the more expensive the tank will be. 

The smallest septic tanks usually start around 500 gallons and are suitable for a 1-bedroom home with 1-2 people. But septic tank systems can vary in size from 500 gallons up to 3,000 gallons or more. 

Average Septic Tank Cost By Size

• 500 gallons - $700
• 750 gallons - $1,000
• 1,000 gallons - $1,200
• 1,250 gallons - $1,700
• 1,500 gallons - $2400
• 2,000 gallons - $2,800
• 3,000 gallons - $3,500+

The figures are estimated assuming a polyethylene septic tank, which is usually the cheapest kind. There are also fiberglass septic tanks and concrete septic tanks, both of which are generally more expensive. 

As a general rule of thumb, you can expect a fiberglass septic tank to be about 20%-30% more expensive than a polyethylene tank of similar size, and a concrete tank is about 25%-40% more expensive than a polyethylene tank of similar size. 

Septic System Installation Costs

1. Basic Conventional System:

   • Cost: $3,000 to $7,000
   • Description: A standard septic system with a tank and a leach field. Suitable for properties with favorable soil conditions.

2. Alternative Systems:

   • Aerobic Treatment Units (ATUs):
     • Cost: $10,000 to $20,000
     • Description: Uses oxygen to break down waste more efficiently. Ideal for areas with high water tables or poor soil conditions.
   • Mound Systems:
     • Cost: $10,000 to $20,000
     • Description: Suitable for areas with shallow soil over bedrock or a high water table. Involves constructing a sand mound.
   • Sand Filter Systems:
     • Cost: $7,500 to $15,000
     • Description: Filters wastewater through sand before it reaches the leach field. Used when soil conditions are poor.
   • Drip Distribution Systems:
     • Cost: $8,000 to $15,000
     • Description: Distributes wastewater evenly through drip lines. Suitable for properties with limited space.

3. Additional Costs:

   • Permits and Inspections:
     • Cost: $500 to $2,000
     • Description: Required by local authorities to ensure the system meets health and safety standards.
   • Site Evaluation and Soil Testing:
     • Cost: $1,000 to $2,000
     • Description: Necessary to determine the appropriate type of system and design.
   • Excavation and Labor:
     • Cost: $1,500 to $5,000
     • Description: Costs for digging and preparing the site for installation.

Septic System Replacement Cost

1. Tank Replacement:

   • Cost: $3,000 to $7,000
   • Description: Replacing the septic tank only, not the entire system. Costs depend on the size and material of the tank.

2. Leach Field Replacement:

   • Cost: $5,000 to $20,000
   • Description: Replacing the leach field, which can be more complex and expensive depending on the size and soil conditions.

3. Complete System Replacement:

   • Cost: $10,000 to $30,000
   • Description: Involves replacing both the tank and the leach field. Costs can vary widely based on the type of system and site conditions.

Septic Permit Costs

You will need to apply for a septic permit if you are installing a new septic system. Acquiring a septic permit involves having an inspection done to make sure your septic system is up to local health ordinances and engineering codes. 

The exact cost of a permit depends on the state where you live. Typically, a residential septic permit costs about $300-$500, while a permit for commercial or industrial locations costs anywhere between $500-$1,500, depending on tank size and the type of septic system it is.

Also, depending on the state in which you live, you may have to apply for other permits such as a building permit, water rights permit, utility permit, occupation permit, and others. Ensure you check with your local housing authority for the specific permits you need to build a new septic tank. 

Septic Tank Maintenance Costs

Regular maintenance is an essential part of ensuring your septic tank is in working order and lasts a long time. Common problems with septic tanks may include excess water, clogged drainage systems, strong odors, ground movements destroying pipes, and tree root infiltration into the drainage system. 

The average home of 4 people requires septic tank maintenance once every 2-3 years. If more people are living in the house, then maintenance should be performed every 1-2 years. 

It is hard to give an exact figure for septic tank maintenance costs as they depend on your location, the severity of the problem, and the type of septic tank system you have (e.g., conventional or engineered). However, most professionals charge somewhere around $300-$400, potentially more if the issue is serious or if you are located in an area with high living costs. 

How Long Can a Septic System Last?

Assuming that you perform regular maintenance and use the system in the way it was intended (i.e., not flushing non-biodegradable materials), a decent septic tank system can last for decades. However, even the best-maintained septic systems will need to be replaced eventually. 

Common signs of a failing septic system include clogged pipes, degradation of the tank, inability to drain properly, puddles seeping up into your yard, excess plant growth on the surface of your drain field, and contaminated water wells. This last issue is serious and can be very dangerous for your health.  

Septic Tank Replacement Costs

Despite what you might think, replacing a septic system is often more expensive than installing a brand new one. Replacing a septic system usually involves removing existing material as well as installing new parts. This involves more time and more labor. 

In the best-case scenario, you can get away with just replacing the malfunctioning parts. Common replacement parts include pumps, tanks, pipes, and drainage ditches. The cost of these can vary heavily depending on the type of system you have and the severity of the damage. All in all, replacing existing parts of a septic tank system can cost anywhere between $500-$3,000, not including labor costs and material costs. 

Septic System Installation Bottom Line

The cost of installing or replacing a septic system in California can vary greatly based on numerous factors. While basic conventional systems are more affordable, properties with challenging conditions may require more expensive alternative systems. Homeowners should plan for additional costs related to permits, site evaluation, and labor. If you need to install a septic tank, it's important to be prepared to cover the costs, which can often exceed $10,000.