Septic System Regulations in Illinois

In Illinois, onsite wastewater (septic) systems are regulated by Illinois Department of Public Health (IDPH), Division of Environmental Health, Private Sewage Program, which sets the statewide code, and permits are issued and inspections carried out by county or local health jurisdictions. Installing, replacing or repairing a septic system here means, in sequence: a site and soil evaluation, a design, a permit application, an inspection while the system is open, and a final as-built record once it is approved.

Who regulates septic systems in Illinois

The state-level regulator is Illinois Department of Public Health (IDPH), Division of Environmental Health, Private Sewage Program (official program page). IDPH holds statewide rulemaking authority and reviews/approves plans directly in areas without a delegated agency, but about 90 local health departments/agencies review and approve private sewage disposal construction plans and issue permits, either under authority of a local ordinance or as an official "agent" of IDPH; counties may enforce ordinances that meet or exceed the state minimums.

The statewide onsite-wastewater code is cited as 77 Illinois Administrative Code Part 905 ("Private Sewage Disposal Licensing Code"). We link the agency's own page above rather than restating specific numeric requirements from it, since those change by rule revision and by local amendment.

The permit sequence

The order of operations is broadly consistent across the country, even though the specific numbers in each step vary by state and often by county. None of the figures below are specific to Illinois; treat this as the shape of the process, and get the actual numbers from the agency linked above or from the county office.

1. Site and soil evaluation. A qualified evaluator (see licensing below) digs test pits or runs a percolation test, and records the soil profile, depth to seasonal water table, depth to any restrictive layer, and slope. This determines whether the lot can support a conventional system or needs an alternative design.
2. Design. Under most state codes, daily design flow is set from bedroom count, not square footage. That flow drives tank capacity, and the soil evaluation sets the drainfield application rate and therefore its size. The designer also lays out setbacks to wells, property lines, surface water, foundations and a reserve/replacement area.
3. Permit application. Submitted to whichever office issues permits here (state agency or county/district health office, per the delegation model above), along with the design and soil work.
4. Installation and open inspection. The installer builds the system, and it is inspected before backfill while it is still open to view.
5. As-built and approval. A final drawing of what was actually built is filed once the system is approved. That as-built is the document a future owner, pumper or inspector needs, and it is what ends up in the county record.

Who can design and install a septic system

Getting septic records in Illinois

Septic records in Illinois are generally held by the county or local health jurisdiction that issued the permit, not by the state agency, and are released under the state's public records law. We have not logged the specific statute name and response deadline for Illinois yet; check with the county office listed on its records page below, or with Illinois Department of Public Health (IDPH), Division of Environmental Health, Private Sewage Program.

Counties in Illinois we hold records for

We hold 2,190 septic records across 66 of 102 Illinois counties. Each county page below shows exactly where its records are kept and how many we hold.

Full Illinois county-by-county index · Open the parcel map

Common questions

Who regulates septic systems in Illinois?

Illinois Department of Public Health (IDPH), Division of Environmental Health, Private Sewage Program. IDPH holds statewide rulemaking authority and reviews/approves plans directly in areas without a delegated agency, but about 90 local health departments/agencies review and approve private sewage disposal construction plans and issue permits, either under authority of a local ordinance or as an official "agent" of IDPH; counties may enforce ordinances that meet or exceed the state minimums.

What is the septic permit process in Illinois?

The sequence is a site and soil evaluation, a design sized from the evaluation and (under most state codes) bedroom count, a permit application, an inspection before backfill, and a final as-built filed once the system is approved. Exact numeric requirements are set by the agency's own code, not restated here.

Who can install a septic system in Illinois?

IDPH-licensed Private Sewage Disposal Installation Contractor (license issued by IDPH; continuing education required to maintain).

How do I get septic records for a property in Illinois?

Septic records are generally held by the county or district health office that issued the permit. See our county-by-county Illinois index for the specific office and portal in each county.

Sources

• https://dph.illinois.gov/topics-services/environmental-health-protection/private-sewage-disposal.html

Regulatory information on this page was researched against official state agency sources and last verified 2026-08-31. It is informational only: the agency linked above is authoritative, and requirements can change. We are not lawyers, not a government body, and not affiliated with, licensed or certified by any agency named on this page.