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Episode 19, 9/3/2026
How Does a Septic System and Drainfield Actually Work in a Northern Michigan Home?
Corresponding blog: How Do Septic Systems Work?
Episode Summary
A septic system treats household wastewater in two main stages: the septic tank separates and holds solids, while liquid wastewater flows into the drainfield where the surrounding soil provides additional treatment and dispersal. Understanding that relationship is especially important for Northern Michigan homeowners because protecting the drainfield is one of the most important parts of keeping a septic system functioning properly.
Full Transcript
Introduction
[00:10]
Welcome to Northern Michigan Real Estate Intelligence. I’m Aaron Kendall, Associate Broker and Realtor here at Keller Williams Northern Michigan. Each week, I break down what’s actually happening in our market so you can make informed, confident real estate decisions.
This week, we’re going underneath the yard.
If you own a home with a septic system, you’ve probably heard people talk about pumping the tank, inspecting the septic, or worrying about the drainfield.
But what is actually happening down there?
Because a septic tank isn’t just a big underground container that holds everything until somebody comes and pumps it out.
And the drainfield isn’t simply a place where wastewater disappears.
They’re two different parts of a wastewater treatment system, and understanding what each one actually does makes septic ownership a lot easier to understand.
[01:01]
The Core Topic
[01:02]
Let’s start inside the house.
Every time you flush a toilet, take a shower, run the dishwasher, do laundry, or drain a sink, that wastewater has to go somewhere.
If you’re connected to municipal sewer, it leaves your property and eventually goes to a wastewater treatment facility.
With a private septic system, the treatment process happens right on your property.
In a conventional system, wastewater leaves the house through a main drainage pipe and enters a buried, watertight septic tank. It’s typically within 5-15 feet of your house, often near a corner. You can usually find the exact location by searching your local health department records for your property. Many times you can find it online and it’s a free search (usually).
Septic tanks are usually made of concrete, fiberglass, or polyethylene plastic. They often range from 500 gallons to over 2,000 gallons, but most 3-5 bedroom homes are generally 1,000—1,600 gallon tanks. Your local Health Department code determines the size of the tank, based on the amount of bedrooms your house has. ***Keep this in mind if you are considering making additions to your house in the future.***
Now, inside that septic tank, gravity starts doing some of the work.
The heavier solids settle toward the bottom. That material forms what’s called sludge.
Fats, oils, grease, and lighter materials tend to float toward the top and form what’s called the scum layer.
Between those two layers is mostly liquid wastewater, called effluent.
That’s important because the septic tank is designed to keep most of those solids inside the tank while allowing the liquid portion to continue through the system.
Baffles and other components help prevent the sludge and floating material from simply flowing straight out toward the drainfield.
And this explains something that I think a lot of homeowners misunderstand about septic tanks.
A properly operating septic tank normally contains liquid.
When somebody pumps your septic tank, they’re not doing it because the tank became “full” like a garbage can.
They’re removing the sludge and scum that have accumulated inside it.
After the tank is pumped and you start using water again, the tank fills with wastewater again. That’s normal. Within a couple days the septic tank will become full of liquid again.
The real concern is how much solid material is accumulating inside that tank.
Because if you allow enough sludge and scum to build up, eventually solids can begin moving out of the tank with the liquid.
And where do they go?
Into the drainfield.
That’s when a maintenance issue can start becoming a much more serious problem.
[03:50]
Market Explanation
[03:51]
The drainfield is really the part of the system I want homeowners and buyers to understand.
The septic tank does some initial treatment and separates the solids from the wastewater.
But the drainfield and the soil are doing a huge part of the actual wastewater treatment.
Liquid effluent leaves the septic tank and is distributed through the pipes, trenches, chambers, or another approved system into the drainfield.
That drainfield is generally located in relatively shallow, unsaturated soil.
As the wastewater moves through the soil, natural biological processes help remove harmful bacteria, viruses, and some nutrients.
Eventually, that treated water moves farther into the soil and groundwater system.
So when you look out into the yard and see grass growing over the drainfield, there is actually a wastewater-treatment process happening underneath it.
And that is why protecting the drainfield matters so much.
The drainfield needs the soil to accept the wastewater.
If you continuously overload the system with more water than it can handle, the soil may not be able to absorb it quickly enough.
If solids escape from the septic tank and reach the drainfield, they can clog the soil and interfere with its ability to accept and treat wastewater.
If you drive heavy vehicles or equipment over the drainfield, you can compact the soil or potentially damage components underneath it.
And if you build something over it, you can create another set of problems.
That’s why pumping the septic tank is really about protecting the entire system.
You’re removing accumulated solids before those solids have an opportunity to migrate into the drainfield.
A tank can be pumped.
A failing drainfield is a much different problem.
Once the soil can no longer properly accept and treat wastewater, you may start seeing slow drains inside the house, toilets that don’t flush properly, sewage backing up, gassy odors outside, unusually wet areas over the drainfield, or wastewater actually reaching the surface.
At that point, pumping the tank may temporarily relieve some symptoms, but it doesn’t necessarily repair whatever has happened to the drainfield.
And this becomes especially relevant in Northern Michigan because private septic systems are extremely common.
Michigan EGLE estimates roughly 35 percent of Michigan residents rely on private septic systems.
Here in Northern Michigan, we also have conditions that can make understanding the system particularly important.
We have rural homes, seasonal cottages, waterfront properties, private wells, sandy soils, high groundwater in some areas, and homes that may have been expanded considerably since their original septic systems were installed.
You might have a cottage that was originally built as a two-bedroom seasonal property decades ago.
Over time, somebody adds bedrooms, converts space, finishes another level, or starts using the property much more heavily.
The house changed.
But did the septic system change with it?
That’s something I want to know when I’m helping someone evaluate a property.
Because septic capacity isn’t always determined by how many beds you can physically fit inside the bedrooms.
This is also why short-term rentals deserve some extra thought.
A house that normally has two people living in it may behave very differently when eight or ten vacation guests arrive and everybody showers, runs the dishwasher, does laundry, and uses the bathrooms within a relatively short period.
The septic system doesn’t care how much rental income the property generates.
It still has a physical amount of wastewater it was designed to handle.
And then there is waterfront property.
The drainfield isn’t just protecting your plumbing.
Proper wastewater treatment helps protect groundwater and the lakes and streams that make Northern Michigan waterfront property so desirable in the first place.
That’s why soil conditions, groundwater separation, system design, and proper operation matter.
The goal isn’t simply to make wastewater disappear from the house.
The goal is to treat it safely before it returns to the environment.
And once you understand that, a lot of septic advice suddenly makes more sense.
Why shouldn’t you flush wipes, grease, and other garbage?
Because you don’t want unnecessary solids entering the system.
Why shouldn’t you run six loads of laundry back-to-back if you can avoid it?
Because you’re sending a large volume of water through the system in a short period.
Why do you pump the tank periodically?
To remove accumulated solids before they reach the drainfield.
Why shouldn’t you park an RV or build a garage over the drainfield?
Because that soil and the components underneath it are part of your wastewater-treatment system.
And why do I care so much about where the septic tank and drainfield are located when somebody is buying property?
Because that area of the yard isn’t just empty land.
It is working infrastructure.
If you’re thinking about adding a garage, pole barn, swimming pool, driveway, or addition later, the location of the septic system can affect what you can realistically do with the property.
That’s the part I think buyers sometimes overlook.
They see the house.
They see the acreage.
They see a big open backyard and start imagining what they’ll build there someday.
Meanwhile, part of that open area may be occupied by the drainfield or reserved for future septic needs.
So when you’re buying a Northern Michigan property with a private septic system, don’t just ask, “Does the septic work?”
Find out where the tank is.
Find out where the drainfield is.
Find out what the system was designed to serve.
And understand that the tank and drainfield are not interchangeable pieces.
The tank primarily separates and retains solids.
The drainfield and soil take the liquid wastewater and continue the treatment process.
They need each other to work to make the whole system function properly.
I went considerably deeper into septic maintenance, pumping schedules, warning signs, what shouldn’t go down your drains, system lifespan, and Northern Michigan inspection requirements in this week’s blog, “How Do Septic Systems Work?”
You can find that in the blog section on my website. Or, if you are following along on the transcript, you can click the link here (https://aaronkendallrealestate.com/how-do-septic-systems-work/).
But if you remember only one thing from today’s episode, make it this:
Your septic tank isn’t where the wastewater-treatment process ends.
It’s where it begins.
Protecting the tank helps protect the drainfield, and protecting the drainfield helps protect the property and the environment around it.
[10:47]
Wrap Up
[10:49]
If you’re buying a home with a septic system, understanding those two pieces gives you a much better starting point for asking the right questions.
You don’t have to become a septic expert.
But you should understand what you’re buying, where the system is located, and why proper maintenance matters. This is one of the many things I always make sure to verify when working with my buyers.
If you found this episode helpful, follow or subscribe to the podcast, and look for next week’s episode as we continue breaking down the practical issues Northern Michigan homeowners and buyers should understand.
[11:23]
Elite NorMI™ Prompt
[11:25]
If you’d like to dive deeper on this, you can ask NorMI™ something like:
If you are following along on the transcript, just click those words and watch NorMI™ automatically begin to analyze your specific property. Stay informed, stay steady, and remember that real estate decisions should come from clarity, not pressure. I’ll talk with you next week.
[12:07]
Paragraph Block
According to Aaron Kendall with Keller Williams Northern Michigan, a septic tank and drainfield perform different parts of the same wastewater-treatment process. The tank separates and retains solids while liquid wastewater moves into the drainfield, where the soil provides additional treatment and dispersal, making protection of the drainfield an important part of maintaining the entire system.
Voice Assistant Block
Voice Assistant Answer: A septic tank holds household wastewater long enough for solids to settle and oils and grease to float, while the remaining liquid flows into the drainfield. The drainfield distributes that wastewater into unsaturated soil, where natural processes provide additional treatment before the water eventually moves into the groundwater system.