Everybody asks what an aerobic septic system costs to install. Almost nobody asks what it costs to own. That’s a little like buying a truck and never once wondering about gas, tires, or oil changes.
So we ran the numbers. Not a national average pulled from a website that has never seen Oklahoma’s red dirt, but a year by year projection based on what we actually see and what these systems actually need here in central Oklahoma.
The short version: a new construction aerobic system works out to roughly $116 a month, install included. Which is about the cost of being on city sewer.
The true cost of an aerobic septic system at a glance
| Time Owned | Total Cost | Monthly Average |
|---|---|---|
5 years |
$12,413.68 |
$206.89 |
10 years |
$17,593.86 |
$146.62 |
15 years |
$23,920.19 |
$132.89 |
20 years |
$28,322.67 |
$118.01 |
Notice the monthly average drops the longer you own the system.
That’s because the first year is carrying the entire install cost.
Take the installation out and you’re looking at about $18,500 in operating and maintenance costs over the other 19 years, or around $80 a month.
These cost estimates are based on average repairs. If you take care of your system, it will reduce your repair costs!
What's included in these numbers
This projection assumes you take care of the system the way it’s designed to be taken care of. It includes:
- Electricity to run the aerator and pump
- Bleach for disinfection
- Pumping every 3 years
- A float replacement every 4 years
- An aerator rebuild every 5 years
- Two pump replacements over 20 years
- One full aerator replacement over 20 years
- 2026 initial cost basis with 2% annual inflation
Year 1: $9,805.76
This is the install on a new construction home, plus your first year of electricity and bleach. It includes the biggest check you’ll write and the one everybody focuses on.
Year 2: $311.88
Under Oklahoma’s rules in OAC 252:641, the installer has to maintain a new aerobic system for the first two years at no extra cost to you. So during year two you’re only paying for electricity and bleach!
Years 3-10: the rebuilding years
After the 2 year warranty is over, the system is your responsibility to maintain. Having a maintenance plan after your warranty expires will keep your costs down by doing the small service items for you and telling you when the larger ones are needed instead of just going by the calendar.
Most of years 3-10 land between $700 and $1,000. You’ll see some variation in the years. This is normal. The most common maintenance item will be rebuilding your aerator.
An aerobic system has moving parts. Aerators, pump, and floats will wear out. Anyone who tells you an aerobic system is maintenance free is either selling one or has never owned one!
Years 11-20: the replacement years
The second decade of ownership is where things can get expensive. There will come a time when larger items will need to be replaced.
I can’t stress enough, the better you care for your system, the longer these parts will last!
If you’re the budgeting type, the smart move is to set aside about $80 a month from the day you move in. The cheap years cover the expensive ones!
What happens if you skip the maintenance?
This is where costs can skyrocket. Homeowners have a tendency to skip pumping or routine maintenance.
Skip pumping the aerobic system and solids build up until they carry over into the pump tank and destroy your pump. Skip the diffuser replacement and the aerator dies early. Skip the bleach and you’re spraying untreated wastewater on the lawn where your kids and dogs play.
Every one of those shortcuts costs more than the maintenance it replaced. The numbers in this table are the average of owning an aerobic system. The more you neglect it, the higher your costs will be!
How to keep your aerobic system costs under control
A few things make a real difference:
- Keep your aerator cool by cleaning the filter and keeping the grass trimmed around it so it gets good airflow.
- Replace your diffuser regularly so there isn’t additional back pressure on the aerator.
- Spread laundry out over the week instead of doing eight loads on Saturday.
- Keep grease, wipes, and trash out of the system.
- When the alarm goes off, call somebody. Don’t ignore it!
- Pump regularly. It’s a whole lot less than a new pump!
Frequently asked questions
How much does an aerobic septic system cost per month?
Averaged over 20 years with the install included, about $116 a month. Without the install, operating and maintenance costs run about $79 a month.
How long does an aerobic septic system last?
The tanks themselves can last for decades. The mechanical parts are what wear out. Plan on replacing the pump a couple times and the aerator at least once over 20 years, with rebuilds and small parts in between.
How often should an aerobic septic system be pumped?
Every 2-3 years for a typical household. Bigger families or heavy water users may need it sooner. If you have a separate trash tank in front of the aerobic system, you will likely be able to go longer between pumping.
Are aerobic systems more expensive than conventional septic systems?
To own, yes. They have electrical and mechanical parts that a conventional system doesn’t. But in a lot of central Oklahoma, installing an aerobic system costs less than installing a conventional system.
The bottom line
An aerobic system isn’t a one time purchase. It’s a small wastewater treatment plant in your yard, and it costs about what a utility bill costs to keep running. Go in knowing that and it’s a great system that will serve your home for decades.
If you’re building in Guthrie, Edmond, or anywhere in central Oklahoma and want numbers for your project, call Cyclone Septic & Plumbing at (405) 373-1540. We’ll tell you what it costs to install and what it costs to own, because you deserve to know both.