Overhead sewer system
What is an overhead sewer system?
An overhead sewer system raises the basement wastewater discharge path above the sewer backup level, using an ejector for basement fixtures while upstairs fixtures drain by gravity. As of Nov 2026, it can suit repeated sewer surcharge, but it requires plumbing reconstruction, electricity and a licensed plumber’s design.
Sources: Illinois Department of Natural Resources. Checked Nov 4, 2026.
By Waterproofing Cost
Published · Updated
How does raising the sewer prevent basement backup?
Illinois DNR describes an ejector collecting wastewater from basement fixtures and the floor drain, then lifting it above flood level before gravity drainage resumes. The raised route keeps backed-up sewage within the sewer piping instead of offering a low opening into the basement.
This addresses sewer backup. For wall or slab leaks, use the basement flood-prevention guide. A sewer conversion does not specify groundwater waterproofing.
When is it a better choice than a backwater valve?
Compare overhead conversion when repeated sewer surcharge makes reliance on a closing valve unattractive. Lombard’s program explains that debris can prevent a check valve from sealing and that house plumbing cannot be used while that valve is closed.
An overhead arrangement can preserve above-grade fixture use during a storm, while basement fixtures depend on the ejector. Compare protected fixtures and failure modes with a backwater valve; neither choice removes maintenance.
How much should you budget for conversion?
As of Nov 2026, Skokie’s Stormwater Task Force page uses $15,000 as an overhead sewer conversion planning estimate. This is a municipal budget reference, not a national installed range or a quote for your house; the page does not establish a current local contractor price.
For comparable offers, request a marked pipe route and separate prices for the basin/ejector, fixture reconnections, excavation, electrical work, permits and restoration. Lombard’s program distinguishes these scopes and excludes some finish restoration from its reimbursement rules; your contractor should still price the complete work.
Which permits and professionals should be involved?
Illinois DNR calls for a licensed plumber and a building-department permit for this work. Contact the local department before construction to confirm the accepted arrangement and inspections. The ejector installation guide covers the wastewater equipment within the larger conversion.
Have the plumber coordinate electrical provision and any foundation penetration with the relevant licensed professionals. Request the approved drawing before a floor or wall is opened; a pump-only proposal leaves the conversion route unresolved.
What happens during an outage or pump failure?
Basement fixtures that rely on the ejector lose drainage during a power outage; Illinois DNR distinguishes those fixtures from upstairs gravity drainage. Ask which fixtures must be left unused and how a high-water condition will be reported.
Keep the installed manual and a sewage-ejector service plan. Call a licensed plumber for backup or equipment faults rather than opening the sewage basin to investigate.
Frequently asked questions
Is an overhead sewer just a sewage ejector pump?
No. The ejector lifts basement wastewater, while overhead conversion also changes the building’s drainage route. A pump replacement alone does not establish an overhead system.
Can upstairs plumbing work during a power outage?
In the arrangement described by Illinois DNR, upstairs fixtures continue to drain by gravity. Basement fixtures served by the ejector depend on power.
Does overhead sewer conversion stop groundwater seepage?
It targets sewage backing up through the sewer connection. Wall and floor water entry need a separate water-control assessment.
Should I get a permit before conversion?
Yes. Illinois DNR identifies a licensed plumber and building-department permit as requirements. Ask your local department which plans and inspections apply.
Sources and dates
Key facts checked . Recorded calculator components retain their original Oct 24, 2026 retrieval date; new technical references were accessed separately for each article.
- Guide To Floodproofing — Overhead Sewer — Illinois Department of Natural Resources. Source publication: not stated; historical prices not adopted. Accessed Nov 4, 2026.
- Overhead Sewer Grant Program — Village of Lombard. Source publication: revised November 2021. Accessed Nov 4, 2026.
- Stormwater Task Force — Village of Skokie. Source publication: FY25 planning discussion; page date not stated. Accessed Nov 4, 2026.
See the full source inventory and calculation limits.
Plan the next step
Get a licensed plumber’s route drawing and comparison with valve protection before accepting conversion. Use the calculator only for separately identified groundwater drainage work; it does not price an overhead sewer.