Unincorporated Frio County, Texas has no general county building-permit program and no county zoning ordinance, because Texas gives counties zoning power only over a few specifically named areas123. The city of Dilley lists its own zoning ordinance4. Septic permits for every address in the county come from the county's Road & Bridge Department56. Floodplain development and driveways onto TxDOT highways need their own permits78.
At a glance
- Building permit
- Not required in unincorporated Frio County; no general county building-permit program found1
- Zoning
- No county zoning ordinance in unincorporated Frio County; the city of Dilley lists its own zoning ordinance234
- Septic (OSSF) permit
- Required from Frio County's Road & Bridge Department; $200 residential, $450 commercial or aerobic59
- Floodplain permit
- Required for development in a mapped Special Flood Hazard Area; valid 1 year7
- Driveway on a TxDOT highway
- Required before the county will issue a 9-1-1 address for the property8
- Well permit
- Production permit needed above 25,000 gallons/day or 17.5 GPM in the Evergreen Underground Water Conservation District; smaller wells must still register10
- RV / manufactured home parks
- No county zoning limits a single unit on your own unincorporated lot; a county rule applies only to rental communities of 2+ spaces1112
- Subdivision
- Plats are reviewed by the county Road & Bridge Department13
Who to call
Septic permits
Frio County Road & Bridge Department
Reviews and approves septic (OSSF) permits, subdivision plats, utility permits within county rights-of-way, road and bridge construction and maintenance, and the 911 addressing system for Frio County
2207 BI 35 E, Pearsall, TX 78061
Also useful
Frio County Courthouse (general government contact)
General Frio County government contact at the courthouse in Pearsall; no separate floodplain-administrator office is listed, so ask here or at the Road & Bridge Department about floodplain development permits
500 East San Antonio Street, Pearsall, TX 78061
Contact details are copied from each office’s official page and were checked against it on October 10, 2026.
Off-grid gear
Going off-grid in Frio County means bringing your own water and power. The kit we’d start with:
- Water Crystal Quest Filter any source — well, rain, or creek — to drinking-clean.
- Power Bluetti Solar generators and home battery backup for living off the grid.
- Septic Soil percolation test kit Run your own perc test before paying an engineer — the first thing a septic office asks about.
- Water Well water test kit Bacteria, nitrates, hardness — know what the well on a parcel is really pumping.
These are affiliate links — we may earn a commission, at no cost to you. As an Amazon Associate, Bolthole Index earns from qualifying purchases.
Do you need a building permit in Frio County, Texas?
No. Unincorporated Frio County has no general residential building-permit program, and Texas counties are not given broad authority to require one1. State law grants that power only in narrow situations, such as fire-code permits for large counties and commercial or multifamily buildings, or residential standards a county formally adopts by resolution14. Whether Frio County has adopted such a resolution is unconfirmed; the Frio County Commissioners Court is the office to ask14. An ordinary single-family home, cabin, barn or shop in unincorporated Frio County does not appear to go through county building-permit review, though the county does issue the septic permit for the system serving it16. Inside the city of Dilley, ask the city, because city rules differ from the county's4.
Who issues building permits and other permits in Frio County, and how do you reach them?
There is no county building or zoning office to call for an ordinary home, because Frio County does not run a general building-permit program1. Septic permits, subdivision plats, utility permits in county rights-of-way and 911 addressing all go through the county's Road & Bridge Department instead615. For floodplain development permits, which the county does regulate without listing a dedicated office, the Frio County Courthouse in Pearsall is the general contact16. A driveway onto a TxDOT-maintained highway needs a TxDOT driveway permit before Frio County will issue a 9-1-1 address8.
Does Frio County have zoning?
Unincorporated Frio County has no zoning ordinance, and Texas law gives counties zoning authority only for a handful of specific areas that do not include Frio County23. The county itself therefore sets no minimum home or lot size, no setbacks, no building-height limit and no zoning districts11. Accessory dwellings, tiny homes and temporary camping on your own unincorporated lot are unrestricted under county rules11. The city of Dilley is different: its ordinance page lists a zoning ordinance, so check the City of Dilley before buying inside city limits4. Even there, septic permits still come from the Frio County Road & Bridge Department6. County zoning does not exist, but the county does review plats when land is divided into new lots13.
How do septic and well permits work in Frio County?
Frio County itself, not the state, issues septic permits for on-site sewage facilities (OSSFs), acting as TCEQ's authorized local agent, and the county's subdivision regulations say the County Engineer's office issues permits and inspects all OSSFs517. A homeowner may do the work directly on a system serving the homeowner's own single-family residence; paid work must be done by a state-licensed person18. The Road & Bridge Department reviews and approves septic applications, with fees set at $200 for a residential system and $450 for a commercial or aerobic system, payable only by money order or cashier's check69. Texas's statewide 10-acre exemption can still apply if a licensed site evaluator signs off, the tract is at least 10 acres with a single dwelling, and every part of the system stays 100 feet from the property line19. Only 35% of Frio County's soils are rated free of severe limits for a conventional septic drain field, so a site evaluation matters even where the exemption doesn't apply20. Frio County sits in the Evergreen Underground Water Conservation District, where a well producing more than 25,000 gallons a day or 17.5 gallons a minute needs a production permit; smaller, exempt wells still must be registered with the district before drilling10.
Can you live in an RV or tiny home on your land in Frio County?
Yes, as far as county rules go. Unincorporated Frio County has no zoning ordinance restricting how you occupy your own land, so there's no county rule limiting RV or tiny-home living, and no minimum home size to meet11. A separate county rule only reaches Manufactured Home/Mobile Home/RV Rental Communities: land split into two or more spaces rented or leased for under 60 months without a purchase option, which needs an Infrastructure Development Plan approved by the County Engineer and Commissioners' Court, plus a County Certificate of Compliance before utilities can connect1221. That rule doesn't reach a single RV, tiny home or manufactured home on your own lot outside a rental community12. Whatever you live in, remember it still needs a compliant OSSF permit if it has plumbing22.
Building a home in Frio County: the steps, in order
First, order a site and soil evaluation for your septic system early, since only 35% of the county's soils are free of severe limitations for a conventional drain field20. Second, apply for your OSSF permit through the Frio County Road & Bridge Department, paying $200 for a residential system or $450 for a commercial or aerobic system, by money order or cashier's check69. Third, if you need a well beyond the district's exempt-well threshold, apply for a production permit through the Evergreen Underground Water Conservation District; even an exempt well must be registered before drilling10. Fourth, if your property is in a mapped Special Flood Hazard Area, get a Floodplain Development Permit before you start work; it's valid for one year and must be renewed if the work isn't finished7. Fifth, if your driveway connects to a TxDOT-maintained highway, get a TxDOT driveway permit first, since Frio County won't issue a 9-1-1 address without one8. Sixth, if you're creating a new lot rather than buying an existing one, check with the Road & Bridge Department on subdivision plat requirements13. Finally, build: there is no countywide building-permit review for an ordinary single-family home outside a floodplain1.
What to check before you buy land in Frio County
Water and drought deserve real attention here: annual precipitation runs about 24.2 inches a year, with severe drought in 30.7% of years, and any well beyond the Evergreen district's exempt-well threshold needs a production permit232410. Septic soils are better than in many counties on this site, with 35% of the land free of severe limitations for a conventional drain field, though a site evaluation is still worth doing before you commit20. Land here is essentially flat, with 100% at 15% slope or less and only 16.1% forested, so clearing costs are usually modest2526. Check FEMA flood maps before you buy: development in a mapped Special Flood Hazard Area needs a county Floodplain Development Permit7. If the tract fronts a TxDOT-maintained highway, budget for a TxDOT driveway permit, since the county won't assign a 9-1-1 address without one8. Property tax runs about 1.6% effectively, with a median bill near $1,751 a year, against a typical home value around $173,743272829.
Watch-outs
- Frio County has no general building-permit program, but it does run its own septic (OSSF) permitting through the Road & Bridge Department, unlike counties where TCEQ permits septic directly; don't assume 'no building permit' means 'no septic permit'622.
- A TxDOT driveway permit is required before Frio County will even issue a 9-1-1 address for a property on a TxDOT-maintained highway; budget for this before you plan access8.
- Any well beyond the Evergreen Underground Water Conservation District's exempt threshold (25,000 gallons/day or 17.5 GPM) needs a production permit, and even smaller wells must be registered before drilling10.
- Whether Frio County has adopted a resolution invoking the state's optional residential building standards is unconfirmed; ask the Frio County Commissioners Court or Road & Bridge Department before you build14.
- Inside the city of Dilley, a city zoning ordinance applies that the county's rules do not4.
Sources
- Bexar County (official) - County Building Permit Authority FAQ (Texas statewide statute) (2026 county census)
- Bexar County (official) - County Land-Use/Zoning Authority FAQ (Texas statewide statute) (2026 county census)
- Local Government Code Chapter 231, County Zoning Authority (Texas statewide rule), quoted and re-checked
- City Ordinances, quoted and re-checked
- Road & Bridge | Frio County, TX (2026 county census)
- Frio County Road & Bridge Department (co.frio.tx.us)
- Floodplain Development Permit Application, quoted and re-checked
- 9-1-1 Addressing Project, quoted and re-checked
- Frio County Road & Bridge Department Fee Schedule, quoted and re-checked
- evergreenuwcd.org, quoted and re-checked
- Texas law on county zoning and building authority
- Order Adopting Fourth Revised Frio County Infrastructure Requirements for Manufactured Home/RV Rental Communities, quoted and re-checked
- Road & Bridge Department, quoted and re-checked
- Local Government Code Chapter 233, County Regulation of Housing and Other Structures (Texas statewide rule), quoted and re-checked
- Road & Bridge Department, quoted and re-checked
- Frio County Courthouse (general government contact) (co.frio.tx.us)
- Road & Bridge | Frio County, TX, quoted and re-checked
- Road & Bridge | Frio County, TX, quoted and re-checked
- Getting a Permit for an OSSF - Such as a Septic System (Texas statewide rule), quoted and re-checked
- 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
- Order Adopting Fourth Revised Frio County Infrastructure Requirements for Manufactured Home/RV Rental Communities, quoted and re-checked
- Getting a Permit for an OSSF - Such as a Septic System, quoted and re-checked
- Annual precipitation: Bolthole Index county data
- Share of years in severe drought: Bolthole Index county data
- Share of land at 15% slope or less: Bolthole Index county data
- Wooded share of land: Bolthole Index county data
- Effective property tax rate: Bolthole Index county data
- Median property tax bill: Bolthole Index county data
- Typical home value (Zillow): Bolthole Index county data
Written October 10, 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.