An overhead sewer is the most effective way to stop sewage from backing up into your Chicago basement. If you’ve watched dirty water bubble up through your basement drain during a heavy rainstorm, then it’s time to look into solutions to see which is right for your home and your budget. Because Chicago’s combined sewer system carries rainwater and sewage in the same pipes, a heavy storm can overload them, and that water looks for the lowest opening it can find. If you are like many Chicago homeowners, that opening is in your basement floor.
At Baethke Plumbing, we’ve been helping Chicago homeowners deal with basement backups for 33 years. We’ve installed hundreds of overhead sewers all over the Chicagoland area, and we’ve seen exactly what works when the next big storm rolls in.
Below, we’ll explain how an overhead sewer prevents a basement backup, what it costs to install in Chicago, and what happens during a power outage, so you can decide if it’s the right fix for your home.
Here’s the CliffsNotes version: An overhead sewer moves your home’s sewer connection up near the basement ceiling, above the level where storm backups reach. Your basement drains empty into a sealed pit, and an ejector pump lifts that wastewater up into the overhead line. Because the old floor-level connection is capped, a backed-up city sewer has no low opening to push through, which keeps your basement as dry as Phoenix, Arizona in July.
What Is an Overhead Sewer?
An overhead sewer is a new plumbing system which routes your home’s main sewer line out through the foundation wall near the basement ceiling, instead of through a pipe under the basement floor.
Most older Chicago homes were built with a gravity system. Every drain in the house, including the floor drain, flows downhill into a main line under the basement floor, then out to the city sewer. The problem is that gravity works both ways. When the combined sewer system fills up during a heavy rain, water can flow right back up that same pipe and into your home. An overhead sewer changes that path.
How Exactly Does an Overhead Sewer Prevent a Basement Backup?
An overhead sewer prevents a basement backup by removing every low opening the city sewer could push water through. It does that with three parts working together.
The Overhead Line
- Toilets, sinks, and tubs on the upper floors drain by gravity into a new line that runs along the basement ceiling. That line exits through the foundation wall, well above the basement floor, and then drops underground to connect to the city sewer. A storm backup would have to rise above that exit point to reach your home.
The Ejector Pit and Pump
- Basement fixtures sit too low to drain into a line near the ceiling. So the floor drain, laundry tub, and any basement bathroom drain into a sealed pit set into the basement floor. When the water in the pit reaches a certain level, a float switch turns on an ejector pump, which pushes the wastewater up into the overhead line.
- Also, don’t forget an ejector pump is different from a sump pump. A sump pump handles groundwater. An ejector pump handles sewage and wastewater from your basement drains.
The Capped Floor-Level Connection
- This is the part that does the real protecting. The old drain line under the basement floor, the one the city sewer used to push water back through, gets removed. With that connection sealed, a backed-up sewer has no path into your basement.
- As a bonus, an overhead sewer usually includes a new cleanout, which makes future sewer rodding and camera inspections easier.
Overhead Sewer vs. Check Valve: Which Is Better?
An overhead sewer gives you the strongest protection, while a check valve is the more affordable option. You don’t need both. Installing a check valve on top of an overhead sewer adds cost without adding meaningful protection.
If your basement has backed up more than once, or you have a finished basement you want to protect, an overhead sewer is usually the better long-term investment. If backups are rare, a check valve can still make a real difference. You can learn more in our guide to basement sewage backups.
How Much Does It Cost to Install an Overhead Sewer in Chicago?
Most overhead sewer installations in Chicago cost between $20,000 to $30,000. That’s a significant investment, and we’d rather you hear the real number from us now than be surprised later. Where your home lands in that range depends on how much work your basement needs.
What Affects the Price
- The number of basement fixtures. Every floor drain, laundry tub, and basement bathroom has to be rerouted to the ejector pit.
- Finished vs. unfinished basement. Opening and restoring drywall and flooring adds cost.
- Concrete work. Installing the pit and capping the old floor-level line means breaking and patching the basement floor.
- The condition of your sewer line. If a sewer camera inspection shows roots or broken clay pipe outside the house, that repair may need to happen at the same time.
- Permits. Overhead sewer work requires a City of Chicago permit and inspection, handled by your plumber.
Is an Overhead Sewer Worth the Cost?
For many Chicago homeowners, yes. One backup in a finished basement can mean ruined flooring, drywall, and furniture, plus a cleanup bill, and it can happen again with the next storm. At Baethke, we give you an upfront, flat-rate price before any work begins, so you can weigh it against what a backup would cost you.
What Happens to an Overhead Sewer During a Chicago Power Outage?
During a power outage, an overhead sewer still keeps the city sewer out of your basement. The capped floor-level connection doesn’t need electricity, so a backed-up city sewer still has no low opening to push through.
Here’s what does change when the power goes out:
- Upstairs drains keep working. Toilets, sinks, and showers on the upper floors drain by gravity into the overhead line, so you can use them normally.
- The ejector pump stops. Without power, the pump can’t lift water out of the pit. Anything that drains into the pit just collects there.
- Hold off on basement water use. Skip laundry, the basement shower, and the laundry tub until the power comes back. If the pit fills completely, water from your own basement drains has nowhere to go.
Chicago storms and power outages often arrive together, so plan ahead. Ask your plumber about backup power for the ejector pump, such as a battery backup or a generator connection, and about a high-water alarm that warns you if the pit is filling up. Baethke Plumbing offers several back up power options of varying budgets.
Is an Overhead Sewer Right for Your Chicago Home?
An overhead sewer raises your sewer connection above the backup level, sends basement drains to an ejector pump, and caps the old low connection. It’s the strongest flood protection available for a Chicago basement.
However, it’s a real investment, but if your basement has flooded before, knowing the next storm can’t push sewage into your home is a priceless piece of mind.
You’re the best candidate for an overhead sewer if you’ve had more than one backup, have a finished basement, or are planning to start a remodel soon. Before we get started, our plumbers always suggest starting with an inspection of your sewer line and basement drains. We’ll show you what we find, explain whether an overhead sewer or a check valve fits your home, and give you an upfront price.
Schedule an overhead sewer consultation with Baethke Plumbing. We’d be glad to help keep your basement dry.
About the author: John Baethke
Overhead Sewer Answers for Chicago Homeowners
Do I need a permit to install an overhead sewer in Chicago?
Yes. Installing an overhead sewer in Chicago requires a City of Chicago permit, and the work must pass a city inspection. A licensed plumber typically pulls the permit and schedules the inspection as part of the job, so homeowners don’t have to handle it themselves.
Do I still need a check valve if I have an overhead sewer?
No. An overhead sewer already caps the low connection that a backed-up city sewer would push through, so adding a check valve doesn’t add meaningful protection. Most Chicago homes need one or the other, not both. A check valve is the more affordable option, while an overhead sewer offers the strongest long-term protection.
Does an overhead sewer need maintenance?
An overhead sewer needs very little maintenance, but the ejector pump should be checked periodically to make sure it turns on and pumps properly. Keep wipes, grease, and paper towels out of basement drains, since they can clog the pump. If your system has a high-water alarm, test it occasionally so you know it will warn you if the pit is filling up.
