Overhead Sewer Conversion in Chicago, IL

What Overhead Sewer Conversion Actually Involves

Instead of below-grade fixtures like a basement floor drain draining down into the main line by gravity, they're rerouted to drain up and into the main line above the point where backups occur, typically with an ejector pump lifting that wastewater to the new connection point.

Why This Actually Stops the Backup Pattern

A backwater valve blocks reverse flow at one point; overhead conversion removes the gravity path that let sewage reach below-grade fixtures in the first place, addressing the structural reason the lowest fixture keeps flooding rather than just blocking the symptom.

When This Is the Right Step

This is a more involved and more expensive project than a backwater valve, so it tends to make sense for a home with a genuinely repeat pattern of storm backups rather than a one-time event.

Permits and Programs Vary by Municipality

Some villages have permit requirements or reimbursement programs for this kind of work; these vary and aren't something we'd state as fact - confirm with your local water or sewer department.

How an Overhead Sewer Works

In a traditional gravity setup, the building drain runs beneath the basement floor and slopes down to the lateral, which carries wastewater to the public sewer. The basement floor drain, and any basement fixtures, sit at the lowest point of the system. When the public sewer fills during a storm, water can flow backward up the lateral and out of those low openings.

An overhead sewer changes that arrangement. The main drain is relocated so it exits the house above the basement floor, often near the ceiling of the basement, before heading out to the lateral. Upstairs fixtures drain by gravity into this higher line. Basement fixtures and the floor drain empty into an ejector basin, and a pump lifts that wastewater up into the overhead line. Because the discharge point is now well above the basement floor, a surcharged street sewer has to rise much higher before it can reach the living space.

Who Benefits Most

Overhead conversions are most common in areas with combined sewers and a history of storm-related basement flooding, which includes much of Chicago and many inner-ring suburbs. Homes with finished basements, basement bedrooms or bathrooms, or valuable mechanical equipment in the basement have the most to lose from a backup and often see the biggest benefit.

The conversion is less useful for homes on separate sanitary and storm sewers without a backup history, or for homes where the basement problem is groundwater seepage through walls and floors rather than sewage coming up through the drain.

What the Conversion Involves

A typical conversion involves breaking the basement floor to install an ejector basin, rerouting basement fixtures to drain into it, installing a pump and discharge line, and running the new overhead main out through the foundation wall. The old underground connection is usually capped or fitted with a check valve. The work requires a licensed plumber and, in most municipalities, a permit.

Before starting, the existing lateral should be camera-inspected. There is little point in investing in an overhead system if the lateral itself is broken or full of roots. Cleaning or repairing the lateral first ensures the new system has a clear path to the street.

Overhead Sewer vs. Backwater Valve

A backwater valve blocks reverse flow at a single point in the line. It is less invasive and less expensive, but it requires the household to stop using water while the valve is closed, and it depends on the flap sealing properly every time. An overhead sewer allows upstairs fixtures to keep working during a storm and does not rely on a flap, but it costs more and depends on the ejector pump.

Many homeowners choose based on budget, how often backups have occurred, and how the basement is used. Some combine both approaches.

Municipal Assistance Programs

Some municipalities in the Chicago area have offered rebates or cost-sharing programs for overhead sewer conversions or backwater valves in flood-prone areas. The availability, amounts, and requirements of these programs change over time, so check with your local public works or building department before planning a project.

We are a drain cleaning referral service and cannot confirm program details for your address, but we can clear and inspect your line so you have the information a plumber or program administrator will ask for.

Maintaining an Overhead System

The ejector pump is the heart of an overhead system, and it needs periodic attention. Check that it cycles properly a few times a year, keep non-flushables out of basement fixtures, and have the basin cleaned every few years. A battery backup or high-water alarm adds another layer of protection.

The overhead line itself rarely needs service, but the lateral beyond it still does. Routine rodding of the lateral, especially in older homes with clay pipe and nearby trees, keeps the whole system working.

Is Your Home a Candidate?

The strongest indicator is a history of basement backups during heavy rain, particularly when neighbors on the same block experience backups at the same time. Homes on combined sewers in older neighborhoods, homes at the low point of a street, and homes with basements set well below street grade are the most exposed. If your basement has taken sewer water more than once, an overhead conversion deserves serious consideration.

Another indicator is how the basement is used. A basement that serves as living space, holds a bedroom or bathroom, or houses a furnace, water heater, and laundry has more at stake in a backup than an unfinished storage area.

Understanding the Investment

An overhead conversion is a significant plumbing project, with costs that depend on the size of the house, how many basement fixtures need to be rerouted, the condition of the existing lateral, and local permit requirements. It is typically much more expensive than installing a backwater valve but offers a different kind of protection.

When weighing the cost, compare it against the cost of a single major backup: cleanup, drywall and flooring replacement, lost belongings, and the time and stress involved. For homes with repeated backups, the conversion often pays for itself after one or two avoided events.

Living With an Overhead Sewer

Day to day, an overhead system works quietly. Upstairs fixtures drain normally, and the ejector pump in the basement runs briefly whenever basement fixtures are used. During heavy storms, the household can continue to use upstairs fixtures as usual, since their wastewater exits above the level of potential backup.

The main thing to remember is that basement fixtures depend on the pump. If the power goes out during a storm, avoid using basement fixtures until power returns, unless the pump has a battery backup.

Overhead Systems in Older Homes

Many Chicago bungalows and two-flats already have overhead systems installed decades ago, sometimes with original pumps and basins. If you have bought an older home with an existing overhead system, have it inspected. Older pumps may be near the end of their life, and basins may need cleaning. Check valves and discharge lines can also wear out over time.

Updating an aging overhead system is usually much simpler and less expensive than installing a new one, and it restores the protection the system was designed to provide.

Frequently Asked Questions