Jefferson County, IL: Owner-Builder Allowed

We could not confirm the current building-permit requirement for private construction in unincorporated Jefferson County, Illinois; ask the Jefferson County Courthouse before work begins¹. Jefferson County has zoning, while Mount Vernon administers its own zoning inside the city and up to 1.5 miles beyond it^2,3,4. Septic plans require separate state or local health approval before construction; start with the Jefferson County Health Department^2,5.

At a glance

Building permit: Confirm with Jefferson County before construction⁶
Zoning: County zoning and subdivision standards apply²
Septic: Septic plan approval required before construction through state or local health authority^2,5
RV living: County rule not confirmed; ask about the parcel and proposed use²
Tiny home: County occupancy rule not confirmed; zoning still applies²
Private well: IDPH or local health permit required for a new well⁷
Owner-builder: Limited state plumbing exemption for qualifying occupants; local plumbing permits and inspections may still apply^8,9

Who to call

Also useful

Jefferson County Courthouse

Starting contact for Jefferson County building-permit and zoning questions

618.244.8000

Jefferson County Courthouse 100 South 10th Street Mt. Vernon, IL 62864

Health department

Jefferson County Health Department

Environmental health, onsite sewage disposal system inspections and private water supplies

(618) 244-7134

4102 S. Water Tower Place Mt. Vernon, IL 62864

One more officeRoads & driveways

Roads & driveways

Jefferson County Highway Department

Utility and load permits on county highways and county right of way

618.244.8031

countyengineer@jeffil.us

750 Old Fairfield Road Mt. Vernon, IL 62864

Online permits →

Contact details are copied from each office’s official page and were checked against it on October 12, 2026.

Do you need a building permit in Jefferson County, Illinois?

We could not confirm the current building-permit requirement for private construction in unincorporated Jefferson County; ask the Jefferson County Courthouse to identify the administering office and required approvals¹. Inside Mount Vernon, the city Building Department issues building permits for erecting, moving, adding to or structurally altering buildings and other structures¹⁰. Septic plan approval remains separate, with IDPH or the local health authority; start with the Jefferson County Health Department^2,5.

Illinois statewide baseline building codes took effect in 2025, although municipalities and counties are not required to adopt their own codes⁶. Illinois does not issue building permits for privately funded construction; any required building permit is administered locally⁶. Qualifying owner occupants, lessee occupants and owners building a single-family residence for their own occupancy may perform plumbing work under a limited state exemption, subject to plumbing-code compliance and inspection; only licensed plumbers may assist⁸. Local plumbing permits and inspections may still be required, and the exemption does not waive general building requirements⁹.

Who handles Jefferson County building permits and zoning questions?

No separate Jefferson County building department could be confirmed, so the practical starting point for an unincorporated parcel is the Jefferson County Courthouse at 100 South 10th Street in Mt. Vernon; the main number is 618.244.8000¹. Ask the courthouse to identify the local official, if any, responsible for building permits, plan review and building inspections.

The location question matters because Illinois assigns private-project building-permit administration to the applicable local government⁶. For sites inside Mount Vernon, the city Building Department handles building permits; the city also administers zoning inside the city and up to 1.5 miles beyond its limits^3,4,10. Septic permits do not move with city zoning: private sewage plan approval remains with IDPH or a local health authority, and Jefferson County identifies its Health Department and Illinois EPA as regulators^2,5. For county-road work, the Jefferson County Highway Department approves utility permits on county right of way and overload or oversize permits on county highways¹¹.

Does Jefferson County, Illinois have zoning?

Jefferson County has zoning in its unincorporated areas, but the correct zoning office depends on location.

Jefferson County has zoning in its unincorporated areas, but the correct zoning office depends on location². The county directs owners within 1.5 miles of incorporated limits to check with that municipality². Mount Vernon administers its own zoning inside the city and up to 1.5 miles beyond it; district rules govern uses, setbacks, height and lot size^3,4. Centralia, a city that reaches into Jefferson County but lies mainly in Marion County, also administers its own zoning¹². Septic plan approval remains with IDPH or the local health authority; Jefferson County identifies its Health Department and Illinois EPA as sewage regulators^2,5.

Jefferson County also identifies a Subdivision Code with subdivision standards, so ask the courthouse which subdivision standards apply before splitting or laying out land². For land outside municipal zoning jurisdiction, ask the Jefferson County Courthouse for the parcel's district, zoning map, subdivision standards and the rules for the proposed use¹. We could not confirm current numeric minimum lot size, minimum dwelling size, setbacks, lot coverage or height limits for unincorporated Jefferson County; ask the courthouse for the applicable district schedule¹.

How do septic permits work in Jefferson County?

Septic permits and zoning approval are separate in Jefferson County, including where a city administers zoning.

Septic permits and zoning approval are separate in Jefferson County, including where a city administers zoning. Jefferson County identifies the Jefferson County Health Department and Illinois EPA as sewage regulators, while IDPH regulates private sewage disposal statewide and local health agencies may act under local ordinance or as IDPH agents^2,5. IDPH or the local health authority must approve private sewage plans before construction⁵.

Start with the Jefferson County Health Department at 4102 S. Water Tower Place in Mt. Vernon or (618) 244-7134; its Environmental Health Division inspects onsite sewage disposal systems and private water supplies¹³. Only 3.1 percent of county soils are rated “not limited” for a conventional septic drain field, so make septic feasibility a purchase contingency: a site evaluation may point to an engineered system, rather than rule septic out¹⁴. Illinois also approves specified privies and alternative toilets for human waste, but other domestic wastewater still needs a conventional private sewage system¹⁵.

Can you live in an RV or tiny home in Jefferson County?

We could not confirm a Jefferson County rule allowing long-term RV occupancy, temporary camping or tiny-home occupancy on a private parcel.

We could not confirm a Jefferson County rule allowing long-term RV occupancy, temporary camping or tiny-home occupancy on a private parcel. Because unincorporated Jefferson County has zoning, ask the courthouse about the parcel's district and describe whether the unit will be temporary, occupied during construction or used as a permanent dwelling^1,2. Do not treat Illinois campground licensing rules as permission to live in an RV on private land; those rules address qualifying campgrounds, not an individual parcel¹⁶.

A tiny house also needs a separate sanitation answer. New private sewage systems require approval before construction, and alternative toilets do not eliminate the requirement for conventional disposal of other domestic wastewater^15,17. Manufactured homes are recognized as dwellings under Illinois rules, but county zoning, building, floodplain and utility requirements may still apply to a particular site¹⁸.

Building a home in Jefferson County: steps in order

Confirm whether the parcel lies in a municipality, within a municipality's zoning reach or in unincorporated Jefferson County; Mt. Vernon administers zoning in the city and up to 1.5 miles beyond it.

Confirm whether the parcel lies in a municipality, within a municipality's zoning reach or in unincorporated Jefferson County; Mt. Vernon administers zoning in the city and up to 1.5 miles beyond it^2,4.
Ask the applicable local office for written confirmation of the building permit, zoning approval, building code, plan review, inspections and occupancy approval required for the house; Illinois leaves private-project administration to local government⁶.
Take the site plan and sewage proposal to the Jefferson County Health Department before construction; septic plans require state or local health approval even where a municipality administers zoning^2,5,13.
Contact the Jefferson County Health Department about the permit for a new private well; IDPH and local health departments review well plans, issue new-construction permits and inspect wells^7,13.
If access touches a state-maintained roadway, obtain the required Illinois Department of Transportation right-of-way permit before work; for county-road right-of-way questions, contact the Jefferson County Highway Department^11,19.
Check floodplain and floodway status before finalizing the building site. In rural areas, qualifying floodway construction needs Illinois Department of Natural Resources approval when the stream drains 10 square miles or more; if no floodway has been delineated, work anywhere in the floodplain generally requires review, while minor work meeting a statewide permit may not need a separate application²⁰.

What should you check before buying land in Jefferson County?

Make the offer contingent on written answers for zoning jurisdiction, subdivision status, legal access, septic feasibility, water and floodplain status.

Make the offer contingent on written answers for zoning jurisdiction, subdivision status, legal access, septic feasibility, water and floodplain status. Jefferson County directs owners within 1.5 miles of incorporated limits to check with the municipality, and Mt. Vernon administers zoning in the city and up to 1.5 miles beyond it^2,4. The county also identifies separate subdivision standards, but we could not confirm current district-by-district minimum lot size, setbacks or dwelling-size rules for unincorporated land².

Soils deserve early attention: only 3.1 percent are rated “not limited” for a conventional septic drain field, even though 94.2 percent of county land has a slope of 15 percent or less¹⁴. IDPH and local health departments review private-well plans, issue permits for new well construction and inspect wells⁷. In rural areas, qualifying floodway work requires state approval where a stream drains 10 square miles or more, and an undelineated floodway can mean review for work anywhere in the floodplain²⁰. Work within a state-road right of way needs an Illinois Department of Transportation permit, while the county Highway Department handles specified county-highway and county-right-of-way permits^11,19. The effective property-tax rate is about 1.7 percent, and the median annual property-tax bill is $2,026¹⁴.

Watch-outs

The current county building-permit rule could not be confirmed, so ask the Jefferson County Courthouse before work begins¹.
Only 3.1 percent of Jefferson County soils are rated “not limited” for a conventional septic drain field; evaluate the site and possible engineered systems before buying¹⁴.
A driveway or other work in a state-maintained road right of way needs an Illinois Department of Transportation permit before work begins¹⁹.

Sources

20 official pages, each quoted and re-checked · written October 12, 2026

Written October 12, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

Off-grid gear

Going off-grid in Jefferson County means bringing your own water and power. The kit we’d start with:

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Compared with neighboring counties

Like 4 of its 6 neighbors, Jefferson County requires a building permit for a home.

Rule	Jefferson County	Marion County	Franklin County	Wayne County	Washington County	Perry County	Clinton County
Building permit	Required	Not required	Required	Not required	Required	Required	Required
County zoning	Yes	No	Not published	No	Yes	Yes	Yes
Septic permits	County Health Dept.	County Health Dept.	Franklin-Williamson Bicounty Health Dept.	County Health Dept.	County Health Dept.	County Health Dept.	County Health Dept.

Cities and towns in Jefferson County

Inside a city or town, that city usually issues building permits and sets zoning; the county’s rules above cover unincorporated land. Septic, wells and floodplain rules usually stay with the county or state everywhere.

Not yet covered: Village of Belle Rive · Blissville Township · Village of Bluford · Village of Bonnie · Casner Township · Village of Dix · Dodds Township · Elk Prairie Township · Field Township · Grand Prairie Township · Village of Ina · McClellan Township · Moores Prairie Township · Nason · Pendleton Township · Shiloh Township · Spring Garden Township · Village of Waltonville · Webber Township · Village of Woodlawn

Answers from the rulebook for Jefferson County

What the ordinances and state agencies actually say — one answer per question, each quoted from the official source and independently re-checked.

Jefferson County rules

Local zoningVaries (with conditions)
County aggregate of local zoning: incorporated municipalities and areas subject to municipal zoning jurisdiction may administer their own zoning, while the county code page directs readers to check the municipality within 1.5 miles of incorporated limits.
- This is an aggregate county claim and does not mean Jefferson County administers every local ordinance.
- The City of Mt. Vernon states that it oversees zoning within the city limits and up to 1.5 miles outside the city.
- Local zoning requirements vary by jurisdiction and zoning district.
- The county code page also states that sewer is regulated by the Jefferson County Health Department and EPA; those requirements remain separate from local zoning.
“If within 1.5 miles of incorporated limits, check with that municipality. County Zoning Statement”
County Code ↗Re-checked Oct 7, 2026
Who permits septicMixed (with conditions)
Private sewage disposal in Jefferson County.
- The county code identifies the Jefferson County Health Department and EPA as regulators.
- IDPH regulates private sewage disposal statewide and local health agencies may act under local ordinance or as IDPH agents.
“Sewer is regulated by the Jefferson County Health Department and Environment Protection Agency (EPA).”
County Code ↗Re-checked Oct 2, 2026
One more reviewed finding on this topic
- Mixed (with conditions) — Private sewage disposal in Jefferson County.
  “Sewer is regulated by the Jefferson County Health Department and Environment Protection Agency (EPA).”
  jeffersoncounty.illinois.gov ↗Re-checked Sep 26, 2026
Subdividing landRegulated (with conditions)
Subdivision in Jefferson County.
- The county code page identifies a Subdivision Code and Article I—Subdivision Standards.
“Chapter 34 | Subdivision Code Article I - Subdivision Standards”
County Code ↗Re-checked Sep 26, 2026
County-wide zoningPresent
The Jefferson County Code (Chapter 8) includes a County Zoning Statement and the county administers Zone Districts with enforced setbacks and minimum lot sizes in unincorporated areas.
Jefferson County IL - County Code ↗From the county’s own site, awaiting a second reviewer

Illinois rules that apply here

Building permitLimited
Privately funded construction in Illinois; the State does not itself issue building permits, while any required permit is addressed by the applicable local government.
- Permit requirements may be imposed and administered by the municipality, village, city, or county having jurisdiction.
- The Illinois Capital Development Board states that statewide building codes became effective 1/1/2025, while local code officials remain the best source for project-specific answers.
statewide building-code effective date: 2025-01-01
“No. If any of these are required, they would be addressed by the unit of local government.”
Illinois Codes FAQ ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- Not required — Issuance of building permits by the State of Illinois for privately funded construction.
  “No. If any of these are required, they would be addressed by the unit of local government.”
  Illinois Codes FAQ ↗Re-checked Sep 9, 2026
Owner-builder exemptionConditional
Owner occupants or lessee occupants of single-family residences, and owners of single-family residences under construction for their own occupancy, performing plumbing planning, installation, alteration, or repair in Illinois.
- The exemption is limited to plumbing work on the specified single-family residence; the cited statute does not establish a general owner-builder exemption for all construction trades or a statewide exemption from building permits.
- The plumbing must comply with the minimum standards in the Illinois State Plumbing Code.
- The plumbing is subject to inspection by the Illinois Department of Public Health or by the local governmental unit if it retains a licensed plumber as inspector.
- The owner, owner occupant, or lessee occupant may not employ anyone other than a plumber licensed under the Illinois Plumbing License Law to assist.
- An occupant must have taken possession of and be living in the premises as their bona fide sole and exclusive residence, or, for a residence under construction, expect to take possession and live there as that residence, with current intent to live there for at least 6 months after completion of the plumbing work or, for a residence under construction, at least 6 months after completion of construction.
- Failure to possess and live in the premises as a sole and exclusive residence for 6 months or more creates a rebuttable presumption that the required intent was lacking.
minimum occupancy period: >= 6 months (After completion of plumbing work; for a residence under construction, after completion of construction.)
“Nothing herein contained shall prohibit the owner occupant or lessee occupant of a single family residence, or the owner of a single family residence under construction for his or her occupancy, from planning, installing, altering or repairing the plumbing system of such residence”
HB5913 Enrolled — Illinois Plumbing License Law amendment ↗Re-checked Oct 4, 2026
2 more reviewed findings on this topic
- Conditional — Privately funded construction in Illinois, including projects performed by an owner-builder, as to state-issued building permits, state plan review, state building-code inspections, and state occupancy permits.
  “No. If any of these are required, they would be addressed by the unit of local government.”
  Illinois Codes FAQ ↗Re-checked Oct 4, 2026
- Conditional — Statewide treatment of local plumbing permits and inspections for qualifying owner occupants performing plumbing work on a single-family residence.
  “Nothing contained in this Act shall prohibit any city, town, village, township or county from providing for a Plumbing Inspector or from requiring permits for the installation and repair of plumbing and collecting a fee therefor, but a city, town, village, township, or county that requires a permit for installation and repair of plumbing may not issue that permit without verification that the applicant has a valid plumbing license or that the applicant is the owner occupant of a single family residence that is the subject of the permit.”
  225 ILCS 320/18 — Local regulation; Department standards ↗Re-checked Oct 4, 2026
Building code adoptedPartial
Building-code requirements statewide in Illinois, including residential and commercial construction subject to the Capital Development Board Act baseline requirements.
- Effective 2025-01-01, Illinois requires statewide baseline building-code requirements.
- Local governments may adopt building codes, but they are not required to adopt codes; jurisdictions that do not adopt a code are treated as non-building-code jurisdictions and must follow the applicable state-law baseline requirements.
- For jurisdictions with adopted codes, local codes must regulate structural design at least as stringently as the applicable IRC, IBC, or IEBC baseline.
- Commercial buildings in non-building-code jurisdictions and state-funded buildings are subject to the state-listed codes and qualified-inspection requirements.
- Residential requirements differ depending on whether the jurisdiction has adopted a compliant building code and whether the home purchaser and builder agree to an alternative code.
statewide baseline effective date: 2025-01-01 · local code structural minimum for residential buildings: IRC minimum structural requirements · local code structural minimum for commercial new buildings: IBC minimum structural requirements · local code structural minimum for existing commercial buildings: IEBC minimum structural requirements
“The State of Illinois recently passed legislation (Public Act 103-0510) changing the Capital Development Board Act to require statewide building codes effective 1/1/2025. [...] Commercial buildings in jurisdictions that have not adopted a building code AND state funded buildings. [...] Starting 1/1/25 local codes must regulate the structural design in a manner that is at least as stringent as the IBC© for new buildings or IEBC© for existing buildings. [...] Residential buildings in jurisdictions that have not adopted a building code where agreed to by the home purchaser and home builder. [...] Residential buildings in jurisdictions that have adopted a building code. [...] Starting 1/1/25 local codes must regulate the structural design in a manner that is at least as stringent as the IRC©.”
Illinois Codes ↗Re-checked Sep 9, 2026
2 more reviewed findings on this topic
- Partial — Building-code framework applicable in Jefferson County.
  “Please be advised that the State of Illinois recently passed legislation (Public Act 103-0510) changing the Capital Development Board Act to require statewide baseline building codes effective 1/1/2025. Locally adopted building codes must comply with the requirements of the Act.”
  Illinois Codes FAQ ↗Re-checked Sep 26, 2026
- Adopted — Statewide baseline building-code requirements for residential construction in Illinois, including jurisdictions with and without locally adopted building codes.
  “Please be advised that the State of Illinois recently passed legislation (Public Act 103-0510) changing the Capital Development Board Act to require statewide baseline building codes effective 1/1/2025. Locally adopted building codes must comply with the requirements of the Act.”
  Building Codes and Regulations ↗Re-checked Sep 26, 2026
InspectionsLimited
Privately funded construction statewide in Illinois, as to inspections performed by the State rather than by a local authority having jurisdiction.
- The Illinois Capital Development Board does not perform building-code inspections for privately funded construction.
- If inspections are required, they are addressed by the applicable unit of local government.
- A local municipality or county may be a non-building-code jurisdiction, in which case applicable state baseline requirements and inspection-certification provisions may apply.
“No. If any of these are required, they would be addressed by the unit of local government.”
Illinois Codes FAQ ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- Not required — Building-code-compliance inspections performed by the State of Illinois for privately funded construction.
  “No. If any of these are required, they would be addressed by the unit of local government.”
  Illinois Codes FAQ ↗Re-checked Sep 9, 2026
Certificate of occupancyLimited
Occupancy permits or certificates for privately funded construction in Illinois.
- The State does not issue occupancy permits for privately funded construction.
- If an occupancy permit is required, it is addressed by the applicable unit of local government.
“No. If any of these are required, they would be addressed by the unit of local government.”
Illinois Codes FAQ ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- Not required — Issuance of occupancy permits or certificates by the State of Illinois for privately funded construction.
  “No. If any of these are required, they would be addressed by the unit of local government.”
  Illinois Codes FAQ ↗Re-checked Sep 9, 2026
SetbacksDistrict specific (with conditions)
County zoning regulations for building or setback lines outside municipalities with municipal zoning ordinances.
- The actual setback distances are established by applicable county zoning districts or other local ordinances.
- Agricultural buildings may be required to conform to building or setback lines.
“to establish building or setback lines”
ilga.gov ↗Re-checked Sep 9, 2026
Building heightDistrict specific (with conditions)
County zoning districts outside municipalities with municipal zoning ordinances.
- The applicable county zoning ordinance determines the actual height limit by district or use.
- No single statewide height measurement was identified.
“including height of buildings and structures”
55 ILCS 5/5-12001 — Authority to regulate and restrict location and use of structures ↗Re-checked Sep 9, 2026
Manufactured homesAllowed (with conditions)
Occupancy of manufactured homes as dwellings, including occupancy in manufactured home communities regulated by IDPH.
- Manufactured home communities with 5 or more sites must be licensed by IDPH, except communities located in home rule units.
- IDPH annually inspects licensed communities for renewal, including water, sewage disposal, electrical systems, lighting, roads, spacing of homes, and garbage disposal.
- Manufactured homes moved since January 1, 1980 must be secured using equipment meeting IDPH standards.
- Effective December 31, 2001, manufactured homes must be installed by an Illinois licensed manufactured home installer or the homeowner and installed according to manufacturer instructions; if unavailable, the IDPH Manufactured Home Installation Code applies.
- Local zoning, building, floodplain, and utility requirements may also apply.
manufactured home community license threshold: >= 5 sites (Communities located in home rule units are excepted from this IDPH licensing statement.) · moved-home tiedown requirement effective date: >= 1980-01-01 · installation requirement effective date: >= 2001-12-31
“designed and situated so as to permit its occupancy as a dwelling place for one or more persons”
Manufactured & Modular Homes/Mobile Structures ↗Re-checked Sep 9, 2026
Septic permitRequired
Construction of a new private sewage disposal system statewide, including systems where a septic tank is replaced, a major component is added or removed, or the absorption field changes by at least 25 percent.
- Plan approval must be obtained from IDPH or the applicable local authority before construction begins.
- Persons constructing, installing, repairing, or modifying the system must notify the Department or local authority at least 48 hours before work begins.
- The rule requires submission of plans, site and system information, bedroom count or design volume, soil or percolation information, owner information, and applicant signature.
notice before commencement: >= 48 hours · absorption-field change threshold: >= 25 percent (The rule treats increasing the field by 25% or more, or removing and replacing 25% or more, as a new system.)
“Plan approval shall be obtained from the Department or local authority prior to beginning any construction of a new private sewage disposal system.”
77 Ill. Adm. Code 905.190 Installation Approval ↗Re-checked Sep 9, 2026
2 more reviewed findings on this topic
- Required — New private sewage disposal systems, including qualifying replacements or major modifications, in Jefferson County.
  “Plan approval shall be obtained from the Department or local authority prior to beginning any construction of a new private sewage disposal system.”
  77 Illinois Administrative Code 905 Private Sewage Disposal Code ↗Re-checked Sep 26, 2026
- Required — Private sewage disposal systems in Illinois, including systems in Jefferson County.
  “Staff also review and approve plans for private sewage disposal systems and alternative private sewage disposal systems before construction.”
  Private Sewage Disposal ↗Re-checked Oct 2, 2026
Septic inspectionLimited
New and replacement surface-discharging private sewage disposal systems covered by Illinois EPA general NPDES Permit ILG62.
- Coverage under the general permit is limited to eligible dischargers.
- Systems not eligible for general-permit coverage may require an individual NPDES permit.
- Periodic inspection, monitoring, and reporting are required under the permit.
“The permit sets discharge limits and requires periodic inspection, monitoring and reporting.”
Illinois Surface Discharge Permit (ILG62) ↗Re-checked Sep 9, 2026
Off-grid sanitationAllowed (with conditions)
Off-grid disposal of human wastes through privies, portable toilets, recirculation toilets, incinerator toilets, and compost toilets statewide in Illinois.
- Other domestic wastes must be disposed of in a conventional private sewage disposal system.
- Compost toilets may also be used for other organic domestic wastes.
- Privies have construction, capacity, venting, maintenance, and abandonment requirements.
- A privy pit must have a minimum capacity of 50 cubic feet per seat.
- A privy must be pumped when filled to within 18 inches of the bottom of the riser.
- Vault privies are required where groundwater or limestone formations are within 4 feet of the bottom of the pit.
- Recirculating toilets must meet NSF International/ANSI Standard 41 and residuals must go to an approved public or private sewage disposal system.
- Incinerator and compost toilets have separate maintenance and disposal requirements; compost toilets must meet NSF International/ANSI Standard 41.
privy pit minimum capacity: >= 50 cubic feet per seat · privy pumping trigger: <= 18 inches from bottom of riser (Pump when filled to within this distance.) · vault-privy groundwater or limestone separation: < 4 feet from bottom of pit (Watertight, non-metal vaults are required where the condition applies.)
“Privies, portable toilets, recirculation toilets, incinerator toilets and compost toilets are approved for private sewage disposal of human wastes.”
77 Ill. Adm. Code 905.130 Human Waste Disposal ↗Re-checked Sep 9, 2026
Well permitRequired
Construction of a new water well, modification of an existing water well, or sealing of an abandoned water well in Illinois.
- A permit must be obtained from the Illinois Department of Public Health or an approved local health department before work begins.
- The application must use Department or approved local health department forms and include a plan and drawing of the proposed construction.
- The plan must include the lot size, slope, property lines, distances to septic tanks, abandoned wells, property lines, seepage fields, sewers, and other contamination sources; driller license number and name; estimated daily pumping capacity if greater than 100,000 gallons per day; well location; owner name and address; well type; estimated depth; well-use type; and proposed aquifer.
- The permit is void if construction has not commenced within one year after issuance.
- The permit fee for constructing, deepening, modifying, or sealing a water well may not exceed $100.
- The Department will deny a permit request when available information indicates groundwater contamination exceeds Class I groundwater standards, subject to the treatment approval provision in subsection (f)(2).
- The permittee must notify the Department, approved local health department, or approved unit of local government by telephone or in writing at least two days before work begins.
maximum water well permit fee: <= 100 USD · permit commencement deadline: 1 year after issuance (Permit is void if construction has not commenced within that period.) · pre-work notification: >= 2 days (Notification may be by telephone or in writing.)
“A permit to construct a new water well, modify an existing water well or seal an abandoned water well shall be obtained from the Department or approved local health department prior to start of work.”
77 Ill. Admin. Code 920.130, Water Well Permit Requirements ↗Re-checked Sep 26, 2026
One more reviewed finding on this topic
- Required — New private water-well construction in Jefferson County, excluding community water wells.
  “In the private water and closed loop systems program, the Illinois Department of Public Health (IDPH) administers the licensing of water well and pump installation contractors and regulates the construction, modification and sealing of all water wells, with the exception of community water wells. In addition, the program administers the registration of closed loop well contractors and regulates the construction, modification, and sealing of all closed loop wells. This program is conducted through agreements with 90 local health departments. A major consideration in constructing these wells is to prevent contamination from the ground surface or shallow ground water, sewage disposal systems and other hazardous sources, from entering the well. To ensure the safety of these water supplies, the IDPH and local health departments review water well installation plans, issue permits for new well construction, and inspect wells.”
  Private Water & Closed Loop Wells ↗Re-checked Oct 4, 2026
Mandatory utility hookupWater and sewer (with conditions)
Each building in Illinois intended for human habitation or occupancy, where the Illinois Plumbing Code applies to its plumbing-system design or installation.
- Water may be supplied by a public water system, semi-private water system, or private water supply constructed under 77 Ill. Adm. Code 920 or 930.
- Sewage may be connected to a public sewer system or a private sewage disposal system constructed under 77 Ill. Adm. Code 905.
- All installations must also comply with applicable State and local laws, ordinances, rules, regulations, and local codes.
- Individually owned residences sharing a common wall or ownership right with ground-floor access, such as townhouses or rowhouses, are separate buildings and require separate connections; a condominium-association residence may instead use one public-water service line to a centralized manifold or meter room with independent shutoff valves, a main shutoff valve at the property line, and compliance with local water-department or water-authority requirements.
- A private water supply may be interconnected with a public water system only when it is located and constructed under 77 Ill. Adm. Code 920 and 925 and the public system is protected against backflow and back siphonage under Section 890.1130; no physical connection is permitted between a potable-water system and a non-potable-water source.
“Each building [...] shall have a connection to a public water system, [...] and a connection to a public sewer system or private sewage disposal system”
77 Ill. Adm. Code 890.170 — Sewer and/or Water Required ↗Re-checked Nov 4, 2026
Agricultural exemptionAvailable
Agricultural experiences conducted as a secondary use with agricultural production on a farm in Illinois.
- The activity must be agriculture-related, a secondary use in conjunction with agricultural production, and occur on a farm.
- The activity must be open to the public with the intended purpose of promoting or educating the public about agriculture, agricultural practices, agricultural activities, or agricultural products.
- The property’s primary use must be agricultural production.
- The exemption prevents a county from requiring a conditional use permit, special use permit, special exception, or variance; the statute does not state that other applicable State or local requirements are waived.
“a county shall not require a conditional use permit [...] or variance for agricultural experiences on property of which the primary use is agricultural production.”
Public Act 102-0492 — Agricultural Experiences Act ↗Re-checked Nov 4, 2026
Driveway accessRequired
Work within the right-of-way of an Interstate, U.S. state route, Illinois state route, or state-maintained roadway, including access-driveway requests to State highways.
- A permit must be obtained before work begins.
- Requirements may vary by IDOT district; the applicant must contact the district office for specific requirements.
- IDOT's access-driveway handbook guides what is allowable for highway access requests.
“Per 605 ILCS 5/4 209, IDOT requires a permit when working within the right-of-way of an Interstate, U.S. state route, Illinois state route, or state maintained roadway. A permit must be obtained prior to the start of any work and a copy of the approved permit must be at the worksite at all times.”
Highway Permits ↗Re-checked Sep 9, 2026
Building in a floodplainRequired
Construction activities in regulated Illinois floodways and, where a floodway has not been delineated, generally work anywhere in the floodplain.
- For downstate streams, IDNR Division permitting applies to floodways of streams draining at least one square mile in urban areas or ten square miles in rural areas.
- In northeastern Illinois, Part 3708 applies to identified floodways in Cook County excluding Chicago, DuPage, Kane, Lake, McHenry, and Will Counties.
- Some minor activities are automatically authorized by statewide or regional permits if their terms and conditions are met.
- For State-owned property, Part 3710 requires a permit for all development activity in FEMA-mapped floodplains.
urban stream drainage area threshold: >= 1 square mile (regulated floodways under Part 3700) · rural stream drainage area threshold: >= 10 square miles (regulated floodways under Part 3700)
“All construction activities in the floodways of streams (the channel and the adjacent portion of the floodplain that is needed to safely convey and store flood waters) in urban areas where the stream drainage area is one square mile or more or in rural areas where the stream drainage area is ten square miles or more must be permitted by the Division prior to construction.”
Permit Program ↗Re-checked Sep 9, 2026
One more reviewed finding on this topic
- Limited — Floodway and certain floodplain construction affecting Jefferson County.
  “All construction activities in the floodways of streams [...] must be permitted by the Division prior to construction.”
  Permit Program ↗Re-checked Oct 4, 2026
Short-term rentalsLimited
Short-term rentals in Illinois where at least one room is rented for fewer than 30 consecutive days and accommodations are reserved in advance, when the hosting platform meets the statutory definition of a re-renter.
- Beginning July 1, 2025, qualifying hosting platforms are subject to Hotel Operators’ Occupation Tax.
- The source establishes tax and registration obligations, not statewide land-use permission; local zoning and licensing may separately apply.
rental period: < 30 consecutive days
“Beginning July 1, 2025, hosting platforms for short-term rentals that meet the definition of “re-renter” are subject to Hotel Operators’ Occupation Tax.”
FY 2025-28, Hotel Operators’ Occupation Tax Updates for Hosting Platforms for Short-Term Rentals ↗Re-checked Sep 9, 2026
Permit feesVariable (with conditions)
Applications and written inquiries for Illinois Department of Natural Resources public-water, dam, and floodway work requiring authorization.
- The Department reviews applications and written inquiries free of charge to determine whether authorization is required when sufficient information is provided.
- A permit application fee may apply under the Department's permit fee schedule.
“January 15, 2014, a new Permit Application Fee went into effect. All applications and written inquiries received will be reviewed free of charge to determine whether the Public Water, dam and/or floodway work proposed requires authorization by the Department, so long as sufficient information is provided for the Department to make that determination.”
Permit Program ↗Re-checked Sep 9, 2026
Permit processPublished (with conditions)
Construction projects in Illinois waterways, floodplains, and wetlands seeking State and Federal authorizations through the joint permit application process.
- The joint application seeks authorizations from the U.S. Army Corps of Engineers, Illinois Department of Natural Resources, Office of Water Resources, and Illinois Environmental Protection Agency.
- The joint application form replaced the former Protecting Illinois Waters application package.
“Construction projects in Illinois' waterways, floodplains and wetlands often require both State and Federal authorization. This joint application is designed to simplify the approval process for the applicant seeking project authorizations from the U. S. Army Corps of Engineers, the Illinois Department of Natural Resources, the Office of Water Resources and the Illinois Environmental Protection Agency.”
Permit Application and Instructions ↗Re-checked Sep 9, 2026
Campground & park staysLimited
Operation of a campground providing temporary parking of recreational vehicles in Illinois; this is not a determination of long-term RV occupancy on an individual private parcel outside the statutory campground definition.
- IDPH annually inspects and licenses covered campgrounds.
- A covered campground includes an area where three or more tents, cabins, recreational vehicles, or other shelters are erected and maintained for camping, or where space is provided for camping or temporary RV parking for 10 or more persons for six or more camping days in a calendar year.
- Campgrounds within home-rule units of government are exempt from this State program.
- IDPH inspects water supply and sewage disposal systems, electrical systems, sanitation, food service, and recreational facilities.
- IDPH reviews construction plans for new campgrounds and major expansions or alterations.
- Local zoning and other local requirements may separately apply.
recreational vehicles or other shelters erected and maintained for camping: >= 3 shelters (One alternative branch of the statutory campground definition.) · persons using space for camping or temporary RV parking: >= 10 persons (Applies for six or more camping days during a calendar year.) · camping days: >= 6 days per calendar year (Applies to the 10-or-more-person branch of the statutory campground definition.)
“State law requires the IDPH to annually inspect and license campgrounds in Illinois. The Campground Licensing and Recreational Area Act defines campground as a recreational area where three or more tents, cabins, recreational vehicles or other permanent or non-permanent type shelters are erected and maintained for camping or where space is provided for camping, temporary parking of recreational vehicles or placing of such tents, cabins, recreational vehicles or other permanent or non-permanent type shelters of any kind for 10 or more persons for six or more camping days during a calendar year.”
Youth Camps and Campgrounds ↗Re-checked Nov 4, 2026
2 more reviewed findings on this topic
- Allowed (with conditions) — Overnight camping in Illinois campgrounds subject to the Campground Licensing and Recreational Area Act.
  ““Camping Day” means any 24 hour period or portion thereof during which the participants remain overnight at the site.”
  Youth Camps and Campgrounds ↗Re-checked Sep 9, 2026
- Limited — Temporary camping in covered Illinois campgrounds; this claim does not establish whether camping is allowed on a private parcel outside the statutory campground definition.
  “Campgrounds within home rule units of government are exempt. Staff inspects the water supply and sewage disposal systems, the electrical systems, general sanitation, food service and recreational facilities. IDPH also reviews construction plans for all new campgrounds and for major expansions or alterations of existing ones.”
  Youth Camps and Campgrounds ↗Re-checked Nov 4, 2026
county building authorityLimited
County building-construction and building-code regulation, including residential structures, in counties meeting the statutory population and metropolitan-area conditions.
- The county must have a population not in excess of 1,000,000.
- The county must be located in the area served by the Northeastern Illinois Metropolitan Area Planning Commission.
- Rules are subject to rules or regulations adopted by the State Fire Marshal under the cited gasoline and volatile-oils statute.
- The county must exempt municipalities located wholly or partly within the county when the municipal building code is equal to the county regulation and local authorities are enforcing that municipal code.
- The rules apply throughout the county, but municipalities may establish higher standards.
- The rules do not apply to construction or alteration of buildings or structures used or to be used for agricultural purposes on a tract zoned and used for agricultural purposes.
- The county board must follow the publication and posting requirements in 55 ILCS 5/5-1063.
- Beginning on the effective date of the amendatory Act of the 92nd General Assembly, a county adopting a new building code or amending an existing building code must provide the building-code identification to the Capital Development Board under Section 10.18 at least 30 days before adoption.
- Violations are petty offenses, and enforcement is by an officer designated by county-board resolution.
- The provision expressly authorizes county building-construction and building-code rules, but the opened text does not expressly use the phrase residential building permit requirement.
population threshold: <= 1000000 persons (The county must be located in the area served by the Northeastern Illinois Metropolitan Area Planning Commission.) · pre-adoption identification period: >= 30 days (Applies to a new building code or amendment under the stated amendatory-Act provision.)
“The county board in any county with a population not in excess of 1,000,000 located in the area served by the Northeastern Illinois Metropolitan Area Planning Commission may prescribe by resolution or ordinance reasonable rules and regulations (a) governing the construction and alteration of all buildings and structures and parts and appurtenances thereof and governing the maintenance thereof in a condition reasonably safe from the hazards of fire, explosion, collapse, contagion and the spread of infectious disease”
55 ILCS 5/5-1064 — Buildings in certain counties of less than 1,000,000 population ↗Re-checked Oct 1, 2026
One more reviewed finding on this topic
- General — Illinois counties adopting and enforcing building codes and issuing building permits for residential construction in unincorporated areas, subject to the statewide baseline framework.
  “A municipality or county is not required to adopt building codes. If they do NOT adopt a building code then they are considered a non-building code jurisdiction and section 10.09-1 of the Capital Development Board Act (20 ILCS 3105) applies. If they do adopt a building code(s) then it must comply with section 10.18 of the Capital Development Board Act (20 ILCS 3105).”
  Illinois Codes FAQ ↗Re-checked Sep 26, 2026

Inside cities and towns in Jefferson County

Municipal rules found while researching the county. They apply inside that city or town, not to unincorporated land.

Local zoningPresent (with conditions)
Zoning within the City of Mt. Vernon and up to 1.5 miles outside the city in Jefferson County, Illinois.
- The City of Mt. Vernon states that it oversees zoning within city limits and up to 1.5 miles outside the city.
- The city page states that zoning districts have separate regulations and may include setbacks, height, and lot-size requirements.
zoning districts in Mt. Vernon: 15 districts
“The City of Mt. Vernon has 15 zoning districts, which include residential, commercial, industrial, agricultural, and special-purpose areas. Each zoning district has its own regulations.”
Zoning ↗Re-checked Oct 7, 2026
SetbacksSpecified
Properties subject to City of Mt. Vernon zoning within the city limits and up to 1.5 miles outside the city.
- Requirements depend on the applicable zoning district.
- The City states that each of its 15 zoning districts has its own regulations.
- Detailed district requirements are in the Schedule of District Regulations within the City’s zoning ordinances.
- Additional subdivision, building-permit, and other approval requirements may apply.
“Zoning divides the city into different areas called zoning districts. Each district has rules that determine: What types of buildings are allowed How properties may be used Requirements such as setbacks, height, and lot size [...] The City of Mt. Vernon has 15 zoning districts, which include residential, commercial, industrial, agricultural, and special-purpose areas. Each zoning district has its own regulations.”
Zoning ↗Re-checked Oct 7, 2026

Still unanswered

We looked and could not find an official answer yet. Silence is not permission — ask the county directly.

Zoning districts — Published zoning districts for unincorporated Jefferson County.
Minimum dwelling size — Residential dwellings in unincorporated Jefferson County.
Minimum lot size — Lots in unincorporated Jefferson County.
Lot coverage — Development in unincorporated Jefferson County.
Living in an RV — Long-term RV occupancy on private land in unincorporated Jefferson County.

3 more unanswered

Camping on your land
Tiny homes
Accessory dwellings

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Living off-grid in Jefferson County, Illinois

Is Jefferson County a good place to live off-grid or homestead?

Jefferson County scores 69/100 on the Bolthole Index, a strong county profile. Its strengths: strong self-sufficiency basics: 45.7″/yr rainfall with little drought and manageable long-term carry cost.

How much does land cost in Jefferson County, Illinois?

Land in Jefferson County runs about $4,940 per acre, based on the latest county data.

What is the water situation in Jefferson County?

Jefferson County gets about 45.7" of rain a year, with severe drought in roughly 2.3% of years.

How remote is Jefferson County?

A representative private-land location has about 6,767 people within a 30-minute drive and 2,591,568 within two hours. The road-network catchments count population across county lines and clusters of smaller cities; straight-line radius values remain available as a comparison.

Building permits, zoning and land rules in Jefferson County, Illinois