Off-Grid Living in Mills County, Iowa

I spent time reviewing Mills County's zoning ordinance, building permit requirements, and environmental health documents to understand what is and is not allowed for someone wanting to live off-grid here. Here is what I found—and critically, what remains unclear and how to confirm it.

The Zoning Picture: County-Level Baseline

Mills County has adopted a Zoning Ordinance that governs land use across all unincorporated areas of the county. This is your starting point if you own raw land outside of any town. The ordinance establishes zone districts and use categories that determine what kind of structures and activities are permitted on your parcel.

Practically, this means: before you buy land or finalize any off-grid plan, obtain a county zoning map and confirm whether your property sits in unincorporated Mills County or within an incorporated municipality such as Malvern, Glenwood, or another town. If you are in unincorporated county, county zoning applies. If you are within a town, that town's zoning ordinance takes precedence (and may be more restrictive). The town's rules may also layer on top of state and county rules. I recommend contacting Mills County Planning & Zoning first to identify your zone district, then asking specifically about residential dwelling use, dwelling size minimums, and whether off-grid occupancy is explicitly permitted in your zone.

Building Permits: The Gate to Off-Grid Construction

This is where the rubber meets the road. Mills County requires a building permit before you construct any occupied dwelling, and the permit application triggers the county's most stringent requirement: proof of a water source and a wastewater system.

The core rule: Your building permit application must document either direct access to public water supply or a properly permitted private well AND either access to a public sanitary sewer system or a properly permitted septic system. You cannot pull a permit for an off-grid house without both of these documented systems in place.

What this means in practice: if you are going off-grid, you need a septic system and a private well. Both must be permitted before or concurrent with your building permit application. You cannot build first and permit later. Mills County applies the 2018 International Property Maintenance Code, which sets minimum standards for construction, occupancy, and maintenance. This code is typically less stringent than the state's 2024 International Residential Code, but the county has adopted the 2018 version as its local standard.

To move forward, contact Mills County Planning & Zoning and request a building permit application package. Ask for clarification on: - Whether the well and septic permits must be completed before the building permit is issued, or whether they can be pulled in parallel. - What documentation the county requires to prove well and septic are "properly permitted." - Whether a deed restriction, county letter, or DNR certification satisfies this proof.

Septic Systems: Mandatory Permitting and Inspection

All septic systems in Mills County require a permit to construct, install, or repair. This is not optional. The county conducts inspections at two critical stages: before construction begins and after the system is built. These inspections verify that the system is properly located (adequate setback from wells, property lines, and surface water) and properly constructed (tank sizing, drain field design, soil suitability).

Iowa's DNR sets baseline standards for all private septic systems statewide: wastewater must be treated in a septic tank as the primary treatment unit, meaning alternative systems like outhouses or direct discharge are prohibited. The county enforces the permit and inspection process; the state sets the technical standards.

To proceed: contact Mills County Planning & Zoning to request a septic permit application. You will likely need: - A soil evaluation (percolation test or equivalent) showing that your land is suitable for septic. - A site plan showing the proposed location of the tank and drain field, plus setbacks from existing wells, property lines, and surface water. - Proof that you have hired (or will hire) a licensed septic system designer or installer to oversee the work. - Once designed, the system must pass the county's pre-construction inspection before installation begins, and a post-construction inspection after it is installed.

Budget 4–8 weeks for this process, and expect costs ranging from $5,000 to $15,000+ depending on your soil conditions and the size of the system needed.

Dwelling Size, Tiny Homes, and RVs: An Unconfirmed Zone

I found no county-specific rules in accessible online documents regarding minimum dwelling size, restrictions on tiny homes, or whether RVs can be occupied year-round on raw land. This gap is significant. It does not mean these uses are permitted without limits; it means I could not confirm specific county rules.

Iowa has no statewide minimum-size law for dwellings, but individual counties and municipalities often impose minimums (commonly 600–800 square feet for primary residences in rural areas). Tiny homes, yurts, and manufactured homes may face zone restrictions or additional permitting requirements that differ widely across the state.

How to confirm: Contact Mills County Planning & Zoning directly and ask: - Is there a minimum square footage for a primary residence in your zone? - Are tiny homes (under 400 sq. ft.) permitted? - Are manufactured homes allowed, and if so, are they subject to additional rules? - Can an RV be occupied year-round on raw land, or only seasonally?

Get answers in writing if possible. If the county cannot answer, ask whether the question defers to state law or to individual town codes. If your property is near or within a town, also contact that municipality's zoning or planning office.

Private Wells: State Standards and County Enforcement

If you do not have access to public water, you must drill a private well and obtain a permit for it. This is a two-level process: the county issues the permit, and Iowa's Department of Natural Resources (DNR) sets the technical standards that govern well drilling, testing, and maintenance.

Under Iowa's Private Well Program, water from a new or substantially modified well must be tested for coliform bacteria (to detect contamination) and nitrate (to assess nutrient runoff). An annual coliform test is required thereafter. Wells must be drilled by a licensed well contractor and must meet minimum isolation distances from septic systems, livestock areas, and other sources of contamination.

The county building permit application requires documented proof of a properly permitted well if you are not using public water. This means you need either: - A completed well permit from Mills County, or - Proof from the DNR that your well meets state standards.

Your sequence: Before applying for a building permit, contact Mills County Planning & Zoning to obtain a private well permit application. You will need to hire a licensed well driller and have them conduct the drilling and initial water quality testing. The well must meet minimum depth and construction standards set by Iowa DNR. Once the well is drilled and tested, you submit the permit application to the county along with the testing results and the driller's certification. The county will verify compliance and issue the permit.

Expect this process to take 2–4 weeks, with costs ranging from $2,500 to $5,000 depending on depth and soil conditions.

Greywater Reuse: Locally Unconfirmed, State Baseline Unclear

I found no county-specific rules on greywater reuse in Mills County's accessible documents. Iowa also has no standalone greywater reuse statute. By default under Iowa's plumbing code, greywater (wastewater from sinks, showers, and washing machines, but not toilets) must be discharged into an approved drainage system—typically a septic system—just like blackwater.

Some states have opened limited pathways for on-site greywater irrigation (for toilets, laundry, or landscape), but Iowa has not done so explicitly. Any greywater reuse proposal would likely require approval from Iowa DNR and your county health office, and no explicitly permitted pathway exists in state statute.

How to confirm locally: Contact Mills County Environmental Health and ask: - Can I use greywater from showers or sinks for landscape irrigation? - Can I install a greywater recirculation system for toilet flushing? - What approval process, if any, applies?

Do not assume that state silence on greywater means it is allowed. Confirmation from the county is essential before you invest in greywater infrastructure.

Rainwater Harvesting: Permitted Statewide, but Confirm Locally

Iowa has no state statutes restricting rainwater harvesting, and the state actively encourages it through the Iowa Rain Campaign. This is good news: rainwater collection from roofs is generally legal and can be a valuable supplement to well water for non-potable uses (landscape irrigation, livestock watering).

However, if you plan a large rainwater collection system with significant storage capacity (e.g., a cistern with 5,000+ gallons), the system may trigger Iowa's plumbing code review or require county health approval. Smaller systems (rain barrels for landscaping) are typically uncontroversial.

How to confirm locally: Contact Mills County Environmental Health and ask: - Can I install a rainwater collection system from my roof? - Are there size limits on storage cisterns? - Can rainwater be used for potable (drinking) purposes if filtered and treated, or only non-potable uses?

Document the county's answer in writing. If the county defers to state law or has no specific rule, note that in writing as well. This protects you if a future building or health inspector raises a question.

Utility Disconnection and Full Off-Grid Operation: The Biggest Gap

I found no explicit county prohibition against disconnecting from utilities, but I also found no explicit permission. This is the most ambiguous area in Mills County's accessible documents.

Iowa state law does not compel utility connection for rural properties where an approved well and septic system are in place. However, some municipalities in Iowa do require utility hookups (especially sewer) as a condition of occupancy permits. Mills County may or may not be one of them.

How to confirm: Contact Mills County Planning & Zoning and ask directly: - Can I legally occupy a residential dwelling that is completely off-grid (no public water, no public sewer, no utility company electric service)? - Are there any county or town ordinances that require hookup to utilities even if I have an approved well and septic? - If I am within a town, does that town require utility connection?

This is a critical question because it affects both your build cost (running utility lines can be expensive) and your long-term ability to occupy the property. Get a clear, written answer before you proceed.

The Practical Next Steps

1. Confirm location. Obtain a county zoning map and confirm whether your property is in unincorporated Mills County or within an incorporated town. If within a town, obtain that town's zoning code as well.

2. Verify zone compatibility. Contact Mills County Planning & Zoning and ask whether residential dwelling use is permitted in your zone and whether off-grid operation is explicitly allowed.

3. Ask the hard questions. Ask about dwelling size minimums, tiny homes, RVs, greywater, rainwater, and utility disconnection. Document all answers in writing.

4. Plan your well and septic in parallel. Before applying for a building permit, have a well driller and septic designer conduct site evaluations. You will need both permits before the building permit can issue.

5. Apply for well and septic permits first. Submit these applications to Mills County Planning & Zoning with all required documentation. Allow 2–4 weeks per permit.

6. Apply for the building permit. Once well and septic permits are approved or in process, submit your building permit application with proof of both systems.

7. Pass inspections. Expect pre-construction and post-construction inspections of your septic system and compliance checks of your well and building code adherence.

This process typically takes 2–4 months from first inquiry to permit issuance, not including actual construction time.

Contacts and Resources

• Mills County Planning & Zoning: Start here for zoning, building permits, and septic questions.
• Mills County Environmental Health: Contact for well, greywater, and rainwater questions.
• Iowa Department of Natural Resources (DNR) Private Well Program: Provides statewide technical standards and water quality testing requirements for private wells.
• Your town clerk or zoning office (if within a municipality): Verify that town rules do not add restrictions beyond county rules.