A commercial septic system is a septic system designed to handle a large volume of wastewater from non-residential establishments or buildings with multiple residences, typically serving more than 20 people per day.
Unlike a residential septic system, a commercial septic system is more complex and larger.
It may include pre-treatment technologies such as grease traps, and the design can incorporate multiple small septic tanks that drain to a dry well or connect to multiple absorption areas on a rotating basis.
Because of their design and function, commercial septic systems can be classified as large-capacity septic systems.
Commercial Septic System Cost
The cost of a commercial septic system can vary widely depending on several factors, including the size of the system, the effluent standard required by local regulations, and the site conditions.
On average, a commercial septic system can cost anywhere from $30,000 to $100,000 although some systems may go for as high as $200,000.
The only way to know the cost for sure is to talk to a contractor for site analysis and estimates.
Commercial Septic System Cost by Size
Just like residential septic systems, size is an important pricing factor in commercial septic systems.
The size of the tank and other components will be influenced by how many people the system is meant to serve per day.
The number of users per septic system will vary depending on the frequency of usage.
For instance, an RV park septic system may be idle for some months while an apartment septic system will be in use throughout the year.
However, an assumption of 75 gallons per day per person or 150 gallons per bedroom is usually used when designing a commercial septic system.
The table below gives more average flow rates depending on the type of commercial septic system:
| Facility | Wastewater flow (Gallons Per Unit) |
| Apartment | 50-70 |
| Campground | 20-40 |
| Hotel | 40-60 |
| Store/Resort | 5-12 |
Once the flow rate has been determined, it can be used to estimate the size of the septic tanks/drain field.
In some cases, the normal size septic tanks are used and looped to create a large-scale septic system.
This can therefore be used as a costing guide. For instance, an apartment that has 10 units that have 2 bedrooms each will have a flow rate of approximately 700 gpd and will therefore need a tank of 1200 gallons.
However, most apartment complexes have an average of 100 units which means the septic system should have a capacity of at least 7, 000 gallons per day.
Here is a table of cost estimates of different septic tank sizes:
| Tank size (capacity in gallons) | price |
| 1200 – 1500 | $1,000 – $2,500 |
| 1500 – 2000 | $2,000 – $3,000 |
| 2000 – 3000 | $2,000 – $3,200 |
| 3000 – 4000 | $2,000 – $3,800 |
| 4000-6000 | $2,500 – $5,000 |
| 6000 – 8000 | $3,000 – $7,000 |
The table only gives the cost estimates of the septic tanks but you will also incur installation and other related costs.
Even though the national installation average price is $7,000, this cost will be significantly higher for commercial systems.
Commercial Septic System Cost by Effluent Standard
The effluent standard required by local regulations will also impact the cost of a commercial septic system.
Higher effluent standards may require more advanced treatment systems, such as an aerobic treatment unit, which will increase the cost.
Additionally, larger commercial properties will generate more wastewater and will require a larger system to handle the volume.
The table below shows estimated costs for commercial septic systems based on effluent standard or wastewater volume:
| Effluent Standard | Estimated Cost |
| Conventional system | $30,000 – $60,000 |
| Advanced system | $60,000 – $100,000 |
Cleaning and Maintenance Costs Associated With a Commercial Septic System
Maintenance is an ongoing cost for any septic system owner.
Because of the potential ramifications of a failed commercial system, the government will require regular inspections and maintenance to ensure everything is working fine.
The septic system will need to be inspected at least once a year to determine the level of sludge and scum in the tank.
Pumping the tank should be done at least once every 1-3 years depending on the size and frequency of use of the system.
The cost of pumping a commercial septic tank can be in the range of $500 to $1,500 but it can be more, depending on the volume of the tank.
Other Factors That Affect the Cost of a Commercial Septic System
Several other factors can impact the cost of a commercial septic system, including:
Inspections
As we have seen, regular inspections are important as they help determine the health of the system.
Furthermore, conducting regular inspections is a legal requirement for all commercial septic systems in most locations.
Inspecting a commercial septic system can cost anything from $300 to as much as $3000 depending on the size and complexity of the system.
Underground Conditions
The site conditions, such as the water table level, terrain, and the type of soil will also have a significant impact on the cost.
If the conditions are ideal for a conventional system, then you will spend less money.
However, if the conditions call for an alternate system, then you may spend as much as $100,000 on installation and cost.
Local Regulations
Depending on your local regulations, you may be required to make some additional installations that will come at an extra cost.
For instance, if your local regulations require a pre-treatment system, that will attract an additional cost (see the subsequent section).
Also, the permit and inspection costs will vary from one region to another.
Pre-Treatment System Costs
It is not uncommon for a commercial septic system to have a pre-treatment system.
In most jurisdictions, there is a legally required spacing that must exist between a septic system and water well.
Pre-treatment systems can help to reduce this distance because they help ensure better treatment of wastewater.
The cost of pre-treatment systems will vary depending on the type of system and the quality of effluent.
For instance, a pre-treatment system for an ultrafiltration process is estimated to cost 12-16 cents/m3 while a pre-treatment of a conventional system is approximated to cost 14-15 cents/m3.
Cost-Saving Measures to Take When Installing a Commercial Septic System
Installing a commercial septic system can be very costly due to its size and other factors highlighted above.
However, there are ways to save money during the installation process without sacrificing the quality and efficiency of the system.
I. Choose the Right Location
Avoid installing the system in areas prone to flooding or where the water table is too high, as this can increase the cost of installation and maintenance.
It is also important to avoid areas with heavy foot or vehicular traffic, as this can damage the system and require repairs or replacement.
II. Use Quality Materials and Components
Investing in high-quality components will reduce the need for repairs and replacements.
Choose durable and long-lasting components such as tanks, pumps, and pipes.
It is also important to ensure that the components are installed correctly to avoid leaks and other issues that can increase maintenance costs.
III. Install a Grease Trap and Effluent Filter
Installing a grease trap will help you reduce the amount of grease and other solids that enter your septic system.
Grease can clog pipes and cause backups, leading to expensive repairs and replacements.
A grease trap will intercept and collect grease and solids, preventing them from entering the system and reducing the need for maintenance.
Similarly, an effluent filter (installed in the septic tank to prevent solids from entering the drain field) can extend the life of the drain field and reduce the need for expensive repairs and replacements.
Effluent filters are relatively inexpensive and easy to install, making them a cost-effective way to improve the efficiency of your septic system.
IV. Hire an Experienced Septic System Professional
Be sure to work with an experienced septic system professional. The professional will help you with the site selection as well as the system design.
These two steps may seem negligible but they can cost or save you a lot of money down the line.
For instance, choosing the wrong location for the septic system may result in pollution of the environment which will require an overhaul of the system.
V. Maintain the system regularly
Regular maintenance is essential for the proper functioning of a septic system and can help prevent costly repairs and replacements.
Schedule regular inspections and pumpings to keep the system running smoothly.
Proper maintenance can also extend the life of the system, saving you money in the long run.
VI. Explore Available Financing Options
It might also be a good idea to explore all financing options available before you embark on the project.
Take advantage of any grants or loans that may be applicable to offset the cost of installing a commercial septic system.
Related: How To Apply For Septic Tank Grant
FAQS
How long does a commercial septic system typically last?
A well-designed septic system should last for at least 30 years.
Even though some factors like frequency of use and level of treatment may impact the longevity of the system, the most important factor is maintenance.
As long as it is maintained well, the system should last for over three decades.
Are there any financing options available for installing a commercial septic system?
Depending on where you live, there might be some financing options for installing a commercial septic system.
These options include loans, grants, and tax incentives, which can help offset the upfront cost of the system.
Can a commercial septic system be expanded if my business grows?
Yes, a commercial septic system can be expanded if your business grows and generates more wastewater.
The expansion will require additional components, such as a larger septic tank and drain field, and may require modifications to the existing system.
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