Bolthole Index

Lake County, Illinois

Zoning, building permits and septic rules in the Village of Old Mill Creek, Illinois

The Village of Old Mill Creek, Illinois (Lake County) zones its own land under the village Development Code1 and has adopted the 2018 International Residential Building Code for all residential construction inside village limits2. Septic permits for lots without public sewer come from the Lake County Health Department, not the village3. We could not confirm the village's building permit procedure, so ask the village before you plan a build.

At a glance

Zoning
Village zoning under the Development Code (Chapter 158)1
Building code
2018 International Residential Building Code, sprinkler requirements excluded2
Building permit
Not confirmed; ask the village (residential code adopted)2
Minimum lot, R-1
15,000 sq ft, 100 ft wide4
Minimum lot, RR
40,000 sq ft, 150 ft wide5
Maximum height
35 ft in R-1 and RR67
Septic permits
Lake County Health Department3
Well permits
Lake County Water Well Program8

Who to call

Septic permits

Lake County Health Department — Onsite Wastewater Treatment System

Septic system review, permits and construction inspections for properties without public sewer in Lake County

847-377-8020

healthehs@lakecountyil.gov

500 West Winchester Road, Libertyville, IL 60048

Contact details are copied from each office’s official page and were checked against it on October 24, 2026.

Off-grid gear

Going off-grid in Village of Old Mill Creek means bringing your own water and power. The kit we’d start with:

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Does Old Mill Creek, Illinois have zoning, and what does it mean for lot size and setbacks?

Yes. The Village of Old Mill Creek adopted its own zoning districts in its Development Code, Chapter 1581. Verified residential districts include RR (rural residential), R-1, R-2, R-3 and R-89.

In the R-1 district, a single-family detached home needs a lot of at least 15,000 square feet and 100 feet of width4. Principal buildings in R-1 need a 30-foot front yard, 10-foot side yards with at least 25 feet combined, and a 50-foot rear yard10. Lot coverage in R-1, counting buildings and paved areas, is capped at 40% of the lot11.

In the RR district, a single-family lot needs at least 40,000 square feet and 150 feet of width5. RR principal buildings need a 50-foot front yard, 30-foot side yards and a 50-foot rear yard12, and coverage is capped at 30%13. Buildings in both districts top out at 35 feet67.

Check which district a lot is in before you buy. We could not confirm the RC district standards or the zoning map, so ask the Village of Old Mill Creek for the current map.

Do you need a building permit in Old Mill Creek, and who issues it?

The village, not the state, is the place to ask. Illinois does not issue building permits for privately funded construction; any permit requirement comes from the local unit of government14.

The Village of Old Mill Creek has adopted the 2018 International Residential Building Code as the minimum standard for all residential construction inside the village, excluding sprinkler requirements2. We could not confirm the village's building permit application, fees or inspection steps, or whether it issues certificates of occupancy, so contact the Village of Old Mill Creek before you start.

Lake County's building permit requirement applies to unincorporated Lake County only15. For land outside the village, see the Lake County page.

How do septic permits work inside Old Mill Creek?

Septic permits for Old Mill Creek lots without public sewer come from the Lake County Health Department16. The county's septic permit process covers incorporated and unincorporated Lake County wherever public sewers do not exist3.

The steps are a soil evaluation by a licensed soil classifier, a system design by a licensed designer or engineer, plan review by the Health Department, and a construction permit applied for by a licensed septic contractor3. The construction permit is valid for 120 days3. Health Department staff inspect construction, and no part of the system may be backfilled until approved17.

Lake County's soil survey rates 0% of soils "not limited" for a conventional drain field, so expect a site evaluation and often an engineered system18. If the lot connects to public sewer, the septic rules do not apply; ask the village whether sewer is available.

What about wells and water in Old Mill Creek?

Lake County's Water Well Program issues permits for construction of all new private, semi-private and non-community water wells, in incorporated and unincorporated Lake County, and inspects each after completion8. Call the Lake County Health Department before drilling.

Can you live in an RV or tiny home in Old Mill Creek?

We could not confirm the village's rules on living in an RV, camping or tiny homes. The village's temporary-use and accessory-use provisions were not located, so ask the Village of Old Mill Creek before parking or placing either one on a lot. Do not rely on county rules: Lake County's tent and camping rules apply to unincorporated Lake County only19.

Building a home in Old Mill Creek: the steps, in order

  1. Confirm the lot's zoning district and dimensions with the village, using the standards above9.
  2. Ask the village for its building permit application, fees and inspection schedule, which we could not confirm.
  3. Design to the 2018 International Residential Building Code the village adopted2.
  4. If there is no public sewer, start the septic process with the Lake County Health Department3.
  5. If you need a well, apply for a well permit from Lake County8.
  6. Ask the village whether a certificate of occupancy is required before you move in.

What stays with Lake County, and what to check before you buy

Septic permits and well permits stay with Lake County, even inside the village38. Lake County's zoning and building permit rules apply only to unincorporated land, so they do not govern lots inside Old Mill Creek20. See the Lake County page for land outside village limits.

Lake County's effective property tax rate is 2.7%21, and the median property tax bill is $8,743 a year22. Floodplain and wetland development can need a watershed permit, so ask about flood zones on any parcel23.

Watch-outs

  • We could not confirm the Village of Old Mill Creek's building permit, inspection and certificate of occupancy rules, though the village has adopted a residential code2; ask the village before buying or building.
  • The 2018 residential code adoption excludes sprinkler requirements but may be modified by later village ordinances2.
  • Village zoning districts differ in lot size and setbacks, so confirm the district for your exact parcel before relying on the figures above9.
  • Lake County's zoning rules apply only to unincorporated land and do not govern lots inside the village20.

Sources

  1. Article 3.4 Residential Districts, Old Mill Creek Development Code (Chapter 158) (Village of Old Mill Creek), quoted and re-checked
  2. Chapter 150 Building Regulations, Old Mill Creek Code (sections 150.01 to 150.03) (Village of Old Mill Creek), quoted and re-checked
  3. Onsite Wastewater Treatment Systems, quoted and re-checked
  4. Article 3.4 Residential Districts, Old Mill Creek Development Code (Chapter 158) (Village of Old Mill Creek), quoted and re-checked
  5. Article 3.4 Residential Districts, Old Mill Creek Development Code (Chapter 158) (Village of Old Mill Creek), quoted and re-checked
  6. Article 3.4 Residential Districts, Old Mill Creek Development Code (Chapter 158) (Village of Old Mill Creek), quoted and re-checked
  7. Article 3.4 Residential Districts, Old Mill Creek Development Code (Chapter 158) (Village of Old Mill Creek), quoted and re-checked
  8. Environmental Health Permit Applications and Forms, quoted and re-checked
  9. Article 3.4 Residential Districts, Old Mill Creek Development Code (Chapter 158) (Village of Old Mill Creek), quoted and re-checked
  10. Article 3.4 Residential Districts, Old Mill Creek Development Code (Chapter 158) (Village of Old Mill Creek), quoted and re-checked
  11. Article 3.4 Residential Districts, Old Mill Creek Development Code (Chapter 158) (Village of Old Mill Creek), quoted and re-checked
  12. Article 3.4 Residential Districts, Old Mill Creek Development Code (Chapter 158) (Village of Old Mill Creek), quoted and re-checked
  13. Article 3.4 Residential Districts, Old Mill Creek Development Code (Chapter 158) (Village of Old Mill Creek), quoted and re-checked
  14. Illinois Codes FAQ (Illinois statewide rule), quoted and re-checked
  15. Building Permits, quoted and re-checked
  16. Lake County Health Department — Onsite Wastewater Treatment System (lakecountyil.gov)
  17. Septic System Construction Inspection, quoted and re-checked
  18. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
  19. § 151.113 Accessory Uses, quoted and re-checked
  20. Unified Development Ordinance, quoted and re-checked
  21. Effective property tax rate: Bolthole Index county data
  22. Median property tax bill: Bolthole Index county data
  23. Permits & Approvals, quoted and re-checked

Written October 24, 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.

Answers from the rulebook for Village of Old Mill Creek

Village of Old Mill Creek’s own rules

  • Building code adoptedAdopted (with conditions)

    New construction and rehabilitation inside Old Mill Creek village limits

    • Adopts the 2018 IBC for new non-residential buildings and the 2018 IEBC for rehabilitation of existing non-residential buildings, each excluding sprinkler requirements, except as may be modified by subsequent village ordinances
    • Adopts the 2018 International Residential Building Code (irbc) for all residential construction, excluding sprinkler requirements, except as may be modified by subsequent village ordinances
    • Amended by ord. 2025-2 passed 3-10-2025; the IBC adoption originates in ord. 2009-0-2 passed 2-9-2009
    • § 150.01 (ord. 60-0-5, 1960) also says the county building ordinance or code is adopted by reference as the village building code; this is not reconciled with § 150.02 on the page and needs checking

    International Building Code edition: 2018 (sprinkler provisions excluded) · International Residential Building Code edition: 2018 (sprinkler provisions excluded)

    “the board of trustees hereby adopts the 2018 version of the international residential building code (irbc), except for any provision imposing sprinkler requirements, as the minimum construction standards for all residential construction within the village of old mill creek, except as may be modified by subsequent village ordinances. (ord. 2009-0-2, passed 2-9-2009; ord. 2025-2, passed 3-10-2025)”
  • Local zoningPresent (with conditions)

    Land inside Old Mill Creek village limits; the village's own zoning districts in its Development Code (Chapter 158) govern use and dimensions

    • Chapter 158 Article 3.4 sets residential district standards (R-1, R-2, RR, RC) adopted by the village; the district map reference in § 156.20 was seen only in a search snippet and not opened
    • Chapter 156 is listed on the official code index as (reserved)
    “§ 3.4-c r-1 single-family residential district. (a) district description. (1) the r-1 single-family residential district (“r-1 district”) is intended to provide for single-family detached homes”
  • Zoning districtsPartial

    Zoning districts of Old Mill Creek village

    • Verified district headings: R-1 (§ 3.4-c), R-2 (§ 3.4-d) and RR (Article 3.4). The RC Residential Countryside district (§ 3.4-L), the § 156.20 district list and the zoning map were not opened
    • Chapter 156 is listed as (reserved) on the official index
    “§ 3.4-b rr rural residential district. § 3.4-c r-1 single-family residential district. § 3.4-d r-2 single-family residential district. § 3.4-e r-3 single-family residential district. § 3.4-f r-8 general residence district.”
  • Minimum lot sizeSpecified

    Single-family detached dwelling in the R-1 single-family residential district inside Old Mill Creek village

    • Density capped at one dwelling unit per acre, subject to transfer development rights in § 3.4-k
    • Minimum lot width 100 feet for single-family detached dwellings

    minimum lot area: >= 15000 sq ft · minimum lot width: >= 100 ft

    “(2) minimum lot area. for every single-family detached dwelling, there shall be provided a lot having an area of not less than 15,000 square feet. (3) minimum lot width. for every lot used for a single-family detached dwelling, there shall be provided a minimum lot width of 100 feet.”
    One more reviewed finding on this topic
    • Specified — Single-family detached dwelling in the RR district (rural residential, Article 3.4) inside Old Mill Creek village
      “(2) minimum lot area. for every single-family detached dwelling, there shall be provided a lot having an area of not less than 40,000 square feet. (3) minimum lot width. for every lot used for a single-family detached dwelling, there shall be provided a minimum lot width of 150 feet.”
  • SetbacksSpecified

    Principal buildings in the R-1 single-family residential district inside Old Mill Creek village

    • Accessory structures to a single-family detached dwelling: minimum setback ten feet from all lot lines
    • Reversed corner side yard 30 feet, with accessory structures not encroaching into the front yard depth of the lot to the rear
    • Special uses may require greater yards as a condition of authorization

    front yard: >= 30 ft · interior side yard each side: >= 10 ft (combined side yards at least 25 ft) · corner side yard: >= 30 ft · rear yard: >= 50 ft

    “1. front yard: a front yard of not less than 30 feet; 2. interior side yard: a side yard on either side of the principal building of not less than ten feet and a combined total of side yards of not less than 25 feet; 3. corner side yard: a side yard along the street side of not less than 30 feet;”
    One more reviewed finding on this topic
    • Specified — Principal buildings in the RR district (Article 3.4) inside Old Mill Creek village
      “1. front yard: a front yard of not less than 50 feet; 2. interior side yard: two side yards on either side of the principal building of not less than 30 feet each; 3. corner side yard: a side yard along the street side of not less than 50 feet;”
  • Lot coverageSpecified

    Lots in the R-1 single-family residential district inside Old Mill Creek village

    • Coverage includes principal building, all accessory buildings and impervious areas

    maximum lot coverage: <= 40 percent of lot area

    “(5) maximum lot coverage. the total ground area occupied by any principal building, together with all accessory buildings and impervious areas, shall not exceed 40% of the total area of the lot.”
    One more reviewed finding on this topic
  • Building heightSpecified

    Buildings and structures in the R-1 single-family residential district inside Old Mill Creek village

    maximum building height: <= 35 ft

    “(6) maximum building height. no building or structure shall be erected or structurally altered to exceed a height of 35 feet.”
    One more reviewed finding on this topic

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Village of Old Mill Creek or Lake County directly.

  • Building permit — New residential construction inside Old Mill Creek village
  • Owner-builder exemption — Owner-built homes inside Old Mill Creek village
  • Inspections — Inspections of new residential construction inside Old Mill Creek village
  • Certificate of occupancy — Occupancy of new homes inside Old Mill Creek village
  • Minimum dwelling size — Single-family dwellings inside Old Mill Creek village
17 more unanswered
  • Living in an RV
  • Camping on your land
  • Tiny homes
  • Manufactured homes
  • Accessory dwellings
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Mandatory utility hookup
  • Agricultural exemption
  • Driveway access
  • Building in a floodplain
  • Short-term rentals
  • Permit fees
  • Permit process

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.

Unanswered questions are usually a sign that Village of Old Mill Creek publishes no rule on the point, not that none exists. Lake County’s page lists the county offices to call.

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