Bolthole Index

Maricopa County, Arizona

Zoning, building permits and septic rules in Avondale, Arizona

Avondale, Arizona (Maricopa County) administers its own zoning ordinance inside city limits1. Building permits for a home or an accessory dwelling come from the city's Development Services Department2. Septic permits for property in Avondale are issued by Maricopa County on behalf of ADEQ3.

At a glance

Zoning
Avondale administers its own zoning ordinance inside city limits1
Building permit
Issued by Avondale Development Services; plans are reviewed before work starts2
Septic
Maricopa County issues septic permits on behalf of ADEQ3
RV living
Floodplain sites: under 180 consecutive days, highway-ready, or permitted and elevated; other districts unconfirmed4
Accessory dwelling
Allowed on qualifying single-family lots, up to 2 bedrooms5
Smallest single-family lot
Ranges from 5,000 square feet to 5 acres by district6
Wells
State well notice; parcels of 5 or fewer acres need local health review first7

Who to call

Building permits

City of Avondale Development Services Department

Building permits, plan review, zoning compliance review, inspections and certificates of occupancy inside Avondale city limits

(623) 333-4000

Septic permits

Maricopa County Environmental Services - Onsite Wastewater Program

Septic (onsite wastewater) applications, Construction Authorizations and final inspections, issued on ADEQ's behalf

602-506-6666

[email protected]

Online permits →

Contact details are copied from each office’s official page and were checked against it on October 16, 2026.

Off-grid gear

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

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Does Avondale, Arizona have zoning, and what does it mean for lot size and RVs?

Yes. Avondale administers its own zoning ordinance inside city limits1. The single-family districts are AG, RR-43, R1-35, RR-18, R1-15, R1-10, R1-8, R1-7, R1-6 and R1-58.

Minimum lot size depends on the district: AG requires 5 acres, RR-43 requires 43,000 square feet, and R1-5 drops to 5,000 square feet6. Building coverage tops out at 15 percent in AG, RR-43 and R1-35, and reaches 45 percent in R1-8 through R1-59. The cited table sets a 30-foot height limit in every single-family district10.

For RVs, the one rule we confirmed applies to flood-hazard areas: an RV must be on site fewer than 180 consecutive days, be fully licensed and ready for highway use, or meet the permit, elevation and anchoring requirements4. We could not confirm a general rule for living in an RV on an ordinary Avondale lot, or a rule for tiny homes or minimum dwelling size; ask Development Services at (623) 333-40002.

Do you need a building permit in Avondale, and who issues it?

Avondale's Development Services Department requires building plans to be reviewed, leading to a building permit, for anyone who plans to build, change or use space or a structure on a single-family property2. Zoning compliance is reviewed as part of the same plan review2.

Applications go through the city's online portal, where an account lets an owner start a residential building permit application2. A certificate of occupancy is required before an accessory dwelling can legally be occupied2.

We could not confirm whether any category of small residential work is exempt, or how owner-builders are treated inside city limits; call Development Services before assuming either. Arizona law does exempt owners who do the work themselves from contractor licensing11.

Can you build an accessory dwelling unit in Avondale?

Yes, on qualifying single-family lots. Avondale allows up to one attached and one detached accessory dwelling on a single-family lot under one acre5. An ADU cannot be a mobile home, recreational vehicle or other movable habitable space, and it is limited to two bedrooms5.

Size is capped at the lesser of 75 percent of the main dwelling's floor area or 1,000 square feet5. An ADU must connect to the same utilities as the main house, and the owner must show adequate electricity, water and sewage disposal12. An ADU that receives a certificate of occupancy on or after September 14, 2024 cannot be a short-term rental unless the owner lives on the same property13.

How do septic permits work inside Avondale?

Septic stays with the county, not the city. ADEQ delegates onsite wastewater permitting to Arizona's counties, and applications go to the county where the property sits, which for Avondale is Maricopa County3. The Maricopa County Environmental Services Onsite Wastewater Program takes questions at [email protected] or 602-506-666614.

A new system needs an approved Notice of Intent to Construct, and the applicant has two years to build after approval; a Notice of Intent to Discharge follows inspection and testing15. Most Avondale homes are on sewer, so this matters mainly where sewer is unavailable15.

When a home with a septic system is resold, the seller must have a qualified inspector inspect it within six months before transfer, and the buyer files a Notice of Transfer within 15 days after16.

What about wells, floods and driveways in Avondale?

Wells are a state matter. A domestic well on a parcel of 5 or fewer acres must be reviewed by the county or local health authority before the application goes to the Arizona Department of Water Resources7.

In flood-hazard areas, manufactured homes must be elevated to the regulatory flood elevation and anchored, and an engineer or surveyor must certify the installation17. In the city's MH District, private driveways within a manufactured-home park or subdivision must be at least 26 feet wide18.

Building a home in Avondale: the steps, in order

  1. Confirm the lot's zoning district and its lot-size and coverage limits6.
  2. Call Development Services at (623) 333-4000 to confirm requirements before submitting2.
  3. Submit building plans through the city's online portal; zoning review happens during plan review2.
  4. If there is no sewer, apply to Maricopa County for a septic permit15.
  5. Pass the required inspections and get a certificate of occupancy before anyone lives in the new space2.

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

Land outside Avondale's city limits falls under Maricopa County's rules; see the Maricopa County page for those. Inside the city, septic permits stay with the county3.

County-level figures: Maricopa County's effective property tax rate is 0.5 percent19, and its median property tax bill is $1,965 a year20. Annual precipitation is about 8.6 inches21. Confirm the district, flood zone and sewer availability for the specific lot before closing.

Watch-outs

  • We could not confirm Avondale's rules on tiny homes, minimum dwelling size, agricultural exemptions or general RV living; ask Development Services at (623) 333-40002.
  • Floodplain RV and manufactured-home rules are stricter than ordinary lots, so check the flood zone before placing either17.
  • Maricopa County's unincorporated-area rules do not apply inside Avondale city limits1.

Sources

  1. Avondale Code § 28-35, Development standards (Avondale), quoted and re-checked
  2. City of Avondale Development Services Department (avondaleaz.gov)
  3. Onsite Wastewater Treatment Facility (Avondale), quoted and re-checked
  4. Avondale Code § 8-46, Standards for recreational vehicles (Avondale), quoted and re-checked
  5. Avondale Code § 28-33, Uses permitted with conditions (Avondale), quoted and re-checked
  6. Avondale Code § 28-35, Development standards (Avondale), quoted and re-checked
  7. Well Permitting & Notice of Intention Forms (Avondale), quoted and re-checked
  8. Avondale Code § 28-35, Development standards (Avondale), quoted and re-checked
  9. Avondale Code § 28-35, Development standards (Avondale), quoted and re-checked
  10. Avondale Code § 28-35, Development standards (Avondale), quoted and re-checked
  11. Persons not required to be licensed; penalties; applicability (Arizona statewide rule), quoted and re-checked
  12. Avondale Code § 28-33, Uses permitted with conditions (Avondale), quoted and re-checked
  13. Avondale Code § 28-33, Uses permitted with conditions (Avondale), quoted and re-checked
  14. Maricopa County Environmental Services - Onsite Wastewater Program (swm.maricopa.gov)
  15. Onsite Wastewater Treatment System Type 4.02–4.23 General Permit (Avondale), quoted and re-checked
  16. Onsite Wastewater Treatment System Type 4.02–4.23 General Permit (Avondale), quoted and re-checked
  17. Avondale Code § 8-44, Standards for manufactured homes (Avondale), quoted and re-checked
  18. Avondale Code § 28-37, Manufactured Home Park District (Avondale), quoted and re-checked
  19. Effective property tax rate: Bolthole Index county data
  20. Median property tax bill: Bolthole Index county data
  21. Annual precipitation: Bolthole Index county data

Written October 16, 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 Avondale

Avondale’s own rules

  • Local zoningPresent

    Land inside Avondale city limits; the city administers its own zoning ordinance.

    “A. Single-family districts. The following table provides the minimum development standards within the specified zoning district:”
  • Zoning districtsPublished

    Zoning districts inside Avondale city limits.

    • The published residential standards identify AG, RR-43, R1-35, RR-18, R1-15, R1-10, R1-8, R1-7, R1-6, and R1-5 single-family districts.
    • The same section identifies R-2, R-3, and R-4 multifamily districts.
    • The code separately contains MH Manufactured Home Park, commercial, and employment zoning districts.
    “District AG RR-43 R1-35 RR-18 R1-15 R1-10 R1-8 R1-7 R1-6 R1-5”
  • Living in an RVLimited

    Recreational vehicles placed on sites in Avondale city flood-hazard areas.

    • The RV must be on site fewer than 180 consecutive days; or be fully licensed and ready for highway use; or meet § 8-32 permit requirements and the elevation and anchoring requirements for manufactured homes in §§ 8-40 and 8-44.

    maximum consecutive days under first alternative: < 180 days

    “All recreational vehicles placed on site shall: (a) Be on site for fewer than one hundred eighty (180) consecutive days;”
  • Accessory dwellingsAllowed (with conditions)

    Accessory dwelling units on qualifying single-family lots or parcels inside Avondale city limits.

    • Up to one attached and one detached ADU is allowed on a single-family lot under one acre.
    • On a lot of one acre or more, up to one attached and one detached ADU is allowed; a second detached ADU is allowed only if at least one ADU is restricted-affordable.
    • ADUs require compliance with building, fire, public-health, and safety codes and adequate public utility services.
    • An ADU cannot be a mobile home, recreational vehicle, or other movable habitable space.
    • Maximum size is the lesser of 75 percent of the existing dwelling's gross floor area or 1,000 square feet.
    • Maximum bedroom count is two.
    • Post-September 14, 2024 certificates of occupancy impose an owner-residency condition for vacation or short-term rentals, subject to the stated grandfather exception.

    maximum ADU size: <= 75 percent of existing dwelling gross floor area (or 1,000 square feet, whichever is less) · maximum ADU size: <= 1000 square feet (or 75 percent of existing dwelling gross floor area, whichever is less) · maximum bedrooms: <= 2 bedrooms

    “Accessory dwelling units (ADUS) are allowed in certain residential zoning districts, subject to the following:”
  • Mandatory utility hookupConditional

    Accessory dwelling units inside Avondale city limits.

    • An ADU must have adequate electricity, water supply, and sewage disposal.
    • The ADU must be connected to the same utilities as the primary single-family dwelling.
    • The owner must demonstrate adequate services and upgrade services if determined inadequate.
    “An ADU shall be supplied with adequate provisions for electricity, water supply, and sewage disposal.”
  • Driveway accessRequired

    Manufactured-home parks and single-family subdivisions in Avondale's MH District.

    • Each unit or lot must have access to a private driveway or access way connected to a public street.
    • The minimum width of private driveways or access ways within the park or subdivision is 26 feet.

    minimum private driveway or access-way width: >= 26 feet

    “The minimum width of private driveways or access ways within the park or subdivision shall be twenty-six (26) feet. Each unit or lot shall have access to a private driveway or access way connected to a public street.”
  • Building in a floodplainRequired

    Manufactured homes and recreational vehicles in Avondale flood-hazard areas.

    • Manufactured homes must be elevated to the regulatory flood elevation and securely anchored.
    • A registered professional engineer or surveyor must certify compliance after installation.
    • New and replacement manufactured homes must provide adequate surface drainage and hauler access and satisfy the additional elevation/piling standards.
    • Recreational vehicles must satisfy the 180-day, highway-ready, or permit/elevation/anchoring alternatives in § 8-46.
    “All manufactured homes that are placed on site or substantially improved shall: (1) Be elevated so that the bottom of the structural frame or the lowest point of any attached appliances, whichever is lower, is at or above the regulatory flood elevation; and (2) Be securely anchored to an adequately anchored foundation system to resist flotation, collapse or lateral movement.”
  • Short-term rentalsLimited

    Accessory dwelling units inside Avondale city limits that receive a certificate of occupancy on or after September 14, 2024.

    • The ADU may not be used as a vacation or short-term rental unless the owner resides on the same property.
    • The residency requirement does not apply to owners who demonstrate a legal right to build the ADU on or before September 14, 2024, unless the stated three-year statute of limitations has expired.

    occupancy rule date: 2024-09-14 (ADUs issued certificates of occupancy on or after this date)

    “An ADU that is issued a certificate of occupancy on or after September 14, 2024, shall not be used as a vacation rental or short-term rental unless the owner resides on the same property.”

Rules another office applies inside Avondale

Avondale does not set these itself; the county, a health district or the state does, and they apply to every address inside its limits.

  • Minimum lot sizeDistrict specific (with conditions)

    Single-family residential districts inside Avondale city limits, including AG, RR-43, R1-35, RR-18, R1-15, R1-10, R1-8, R1-7, R1-6, and R1-5.

    • The minimum net site area varies by district: AG 5 acres; RR-43 43,000 square feet; R1-35 35,000 square feet; RR-18 18,000 square feet; R1-15 15,000 square feet; R1-10 10,000 square feet; R1-8 8,000 square feet; R1-7 7,000 square feet; R1-6 6,000 square feet; R1-5 5,000 square feet.

    minimum net site area: AG: 5 ac.; RR-43: 43,000 sq. ft.; R1-35: 35,000 sq. ft.; RR-18: 18,000 sq. ft.; R1-15: 15,000 sq. ft.; R1-10: 10,000 sq. ft.; R1-8: 8,000 sq. ft.; R1-7: 7,000 sq. ft.; R1-6: 6,000 sq. ft.; R1-5: 5,000 sq. ft.

    “Minimum net site area (square feet) 5 ac. 43,000 35,000 18,000 15,000 10,000 8,000 7,000 6,000 5,000”
  • Lot coverageDistrict specific (with conditions)

    Single-family residential districts inside Avondale city limits.

    • Maximum building coverage is 15 percent in AG, RR-43, and R1-35; 30 percent in RR-18; 20 percent in R1-15; and 40, 45, 45, 45, and 45 percent in R1-10 through R1-5 respectively.

    maximum building coverage: AG 15%; RR-43 15%; R1-35 15%; RR-18 30%; R1-15 20%; R1-10 40%; R1-8 45%; R1-7 45%; R1-6 45%; R1-5 45%

    “Maximum building coverage 15% 15% 15% 30% 20% 40% 45% 45% 45% 45%”
  • Building heightDistrict specific (with conditions)

    Single-family residential districts inside Avondale city limits.

    • The cited table sets a 30-foot maximum height in each listed single-family district.

    maximum height: 30 feet

    “Maximum height 30' 30' 30' 30' 30' 30' 30' 30' 30' 30'”
  • Who permits septicCounty

    Onsite wastewater systems serving property in Avondale city, administered by Maricopa County under ADEQ delegation.

    • ADEQ retains statutory authority while delegating permitting to counties.
    • Applications must be submitted to the county where the property is located.
    “ADEQ has authority for issuing permits for OWTFs and has delegated this authority to each of the 15 counties, which issue permits on behalf of ADEQ.”
  • Septic permitRequired

    New onsite wastewater treatment facilities serving property in Avondale city where sewer is unavailable or the facility is otherwise covered by the onsite wastewater program.

    • The Type 4.02–4.23 general permit covers flows from 0 to 24,000 gallons per day.
    • An approved Notice of Intent to Construct authorizes construction.
    • The applicant has two years to construct after approval.
    • After construction, inspection, and testing, a Notice of Intent to Discharge is required before discharge authorization.

    covered design flow: <= 24000 gallons per day (Type 4.02–4.23 general permit)

    “this permit is for septic systems with flows from 0 to 24,000 gallons per day, including standard onsite and alternative systems.”
  • Septic inspectionRequired

    Property served by a conventional septic tank or alternative onsite system in Avondale city when the home is being resold.

    • The inspection is triggered by resale by an owner or with assistance from a real-estate professional.
    • The seller must retain a qualified inspector within six months before transfer.
    • The buyer must submit a Notice of Transfer within 15 calendar days after transfer.
    • For Maricopa County, the Notice of Transfer is submitted according to the county-specific instructions.

    inspection timing: 6 months before transfer · buyer Notice of Transfer deadline: 15 calendar days after transfer

    “the seller of a property served by a conventional septic tank or alternative system shall retain a qualified inspector to perform the transfer of ownership inspection within six months before the date of property transfer.”
  • Well permitLimited

    Wells drilled, deepened, replaced, or modified for property in Avondale city.

    • ADWR lists a Notice of Intention to Drill, Deepen, Replace or Modify a Well for other well types.
    • Non-exempt wells in an Active Management Area use a permit application.
    • Exempt wells and water-production wells outside an AMA generally use the Notice of Intention process.
    • Domestic wells on parcels of five acres or fewer require prior review by the applicable county or local health authority.

    exempt-well pump capacity: <= 35 gallons per minute · domestic parcel prior-review threshold: <= 5 acres

    “if water from your well, or existing well being modified or deepened, will be used for domestic purposes on a parcel of land of 5 or fewer acres, the applicable county or local health authority must first review your application prior to submittal to the department of water resources.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Avondale or Maricopa County directly.

  • Building permit — Building permits for construction inside Avondale city limits.
  • Owner-builder exemption — Owner-builders performing construction inside Avondale city limits.
  • Minimum dwelling size — Minimum dwelling size inside Avondale city limits.
  • Tiny homes — Tiny-home occupancy inside Avondale city limits.
  • Off-grid sanitation — Off-grid sanitation inside Avondale city limits.
1 more unanswered
  • Agricultural exemption

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 Avondale publishes no rule on the point, not that none exists. Maricopa County’s page lists the county offices to call.

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