Rolling Texas Hill Country limestone hills with live oak motts, Ashe juniper, and a clear creek over white limestone cobble.
Bexar County No county building code

Barndominium Builders in Bexar County, TX

Bexar County wraps San Antonio in 1,240 square miles, and the buildable acreage is the unincorporated ring outside the city limits — north into the limestone above the Balcones Escarpment, south and east into the clay. The county is blunt about what it can and cannot do there. Its Fire Marshal permits commercial, publicly accessible and multi-family buildings under the county fire code, and the county states in writing that it has no legal authority to regulate residential construction, inspect it, or issue a residential certificate of occupancy. There is no zoning either. What is left is not nothing. The septic permit is the county's, and covers nearly the whole county. A state permit can sit on your parcel: the Edwards Aquifer recharge zone crosses the north. Disturbing an acre of soil costs $500. A well is permitted, not merely drilled. And in a city's ETJ you can be made to plat.

Bexar County at a glance

County
Bexar County
Population
2,160,088
Where we build
San Antonio, Comal County, Guadalupe County, Bandera County

ZIPs 78002, 78006, 78023, 78073, 78101, 78109, 78112, 78152 and more

Site visits
Site walks arranged throughout Bexar County, San Antonio included
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Building conditions in Bexar County

What actually changes from one Texas jurisdiction to the next: who issues the permit, whether the residential code is enforced there at all, what the structure has to be engineered to, and what the ground is like. These are the numbers your drawings have to satisfy.

Build conditions for Bexar County , Texas . BUILD CONDITIONS BEXAR COUNTY, TXBexar CountyNO COUNTY BUILDING…ADOPTED RESIDENTIAL CODENO COUNTY BUILDING…This jurisdiction publishes no design wind speed. It is settled in writing with the authority overyour parcel before the frame is ordered.ZONING · NONE — A TEXAS COUNTY HAS NO POWER T…No zoning minimum; 1.5 acres of usea…Local Government Code sec. 233.153(d)(2) bars a commissioners courtfrom adopting or enforcing zoning, and Bexar County's own published…PUBLISHED BEXAR COUNTY PERMIT FEES$500 storm water quality site develo…There is no county impact fee and no county building permit fee fora house. The storm water quality permit and the post-construction…WHO ISSUES THE PERMITBexar County Public Works, Developme…1948 Probandt St., San Antonio, TX 78214. Phone 210-335-6700, lobby8:00am to 4:45pm Monday to Friday. Storm water quality…
Build conditions for Bexar County, drawn from the sourced facts on this page. Every figure above is cited in the quick-facts panel below, with its source and vintage.
The county says it cannot regulate a house, and cites the fire-code subchapter for the permits it does issue
Bexar County's Fire Marshal answers the question directly: "unless a residential building permit was issued on a voluntary basis, the County does not have legal authority to regulate residential construction, conduct residential construction inspections, or issue a residential Certificate of Occupancy." The permit it does issue rests on "TEXAS LOCAL GOVERNMENT CODE, TITLE 7, CHAPTER 233 - SUBCHAPTER C" — the county fire code, available only to counties over 250,000 population — and not on Subchapter F, the residential building code subchapter a commissioners court has to adopt by order. The county's own permit guidance spells out the limit: the Fire Marshal building permit "does not apply to single family residential homes (including duplexes and triplexes)."

Bexar County Fire Marshal's Office, New Construction FAQs, bexar.org, rendered and read 1 September 2026; Bexar County Public Works, Public Works Permits Verification Guidelines, page 2 item H, updated 6 October 2025

A state permit on land with no building code — and acreage is the way out of it
The Edwards Aquifer recharge and contributing zones cross Bexar County, and both subchapters of the state rule name the county on their face: 30 Texas Administrative Code Chapter 213 is titled for "Medina, Bexar, Comal, Kinney, Uvalde, Hays, Travis, and Williamson Counties." TCEQ's own page for homeowners says construction at private residences on the recharge or contributing zones is subject to those rules, and that an individual plan may not be required if "the construction of your residence is on a lot that is larger than five acres, with no more than one single-family residence located on that lot," or if impervious cover does not exceed 20 percent — where impervious cover "includes rooftops, driveways, concrete pads, sheds, sidewalks." Otherwise you file a Water Pollution Abatement Plan or a Contributing Zone Plan with TCEQ. On a one-acre lot, 20 percent is 8,712 square feet; a shop apron and a long concrete drive spend that quickly. Rainwater harvesting can be used to bring the adjusted figure back under.

TCEQ, Edwards Aquifer: Private Residences, tceq.texas.gov/permitting/eapp/edwards-aquifer-private-residences, rendered 1 September 2026; 30 Texas Administrative Code ch. 213, subchapter titles read on the Texas Secretary of State TAC portal, 1 September 2026

Bexar County is the septic authority for the entire county except four small cities — San Antonio included
TCEQ's authorized agent register lists the "BEXAR COUNTY AUTHORIZED AGENT" as serving the "entire County except Cities of Elmendorf, Hill Country Village, Shavano Park, and Town of Hollywood Park," and prints the rule for reading it: "Do you live within the limits of a city? Find the name of the city under the Authorized Agent column. If the city is not listed, contact the county." The county's own order says the same in its section 6. So the septic answer across almost all of Bexar County, including the second-largest city in Texas, is a county answer.

TCEQ On-Site Sewage Facility Authorized Agent search (OARS), www6.tceq.texas.gov, Bexar County query run 1 September 2026; Order Adopting Regulations of Bexar County, Texas for On-Site Sewage Facilities, sec. 6, adopted 6 June 2006, TCEQ approval order 7 July 2006

The septic order kills the ten-acre exemption in the county's own words, and puts an engineer's seal on every design
Section 10 of the Bexar County septic order is an exhaustive list of where the county goes beyond the state rule, lettered A to P. Three of them change what a barndominium buyer must do. "Elimination of the Ten-Acre Exemption. There is no exemption from the Regulations for a single-family dwelling located on a tract of land that is ten acres or greater." "All on-site sewage facility designs submitted to Bexar County are to be prepared by a professional engineer or registered professional sanitarian registered by the State of Texas and shall bear the seal of the engineer or sanitarian" — the state would let the owner or the installer prepare planning materials for a standard system. And the minimum is "one and one-half (1½) acre of useable land outside of any easements and right-of-way dedications" on a private well, against the state's one acre, with a 150-foot setback from the well to the drainfield. The licence to operate then runs five years and has to be renewed.

Order Adopting Regulations of Bexar County, Texas for On-Site Sewage Facilities, sec. 10 paras. B, C, G, H and L — bexar.org/DocumentCenter/View/30421/OSSF, scanned original read page by page 1 September 2026; 30 Texas Administrative Code secs. 285.4(a)(1) and 285.5(a)(1)

Disturb an acre of soil and the county charges $500 before you start
The permit that actually gates a rural build here is not a building permit. "A Bexar County Storm Water Quality Permit is required when one (1) or more acres of soil are being disturbed on the site or as part of Common Plan of Development. You need an issued SWQ Permit before disturbing soil on a site." The fee is $500, the first review takes 30 days and resubmittals 15, and a stormwater pollution prevention plan goes in with it. A post-construction permit at $50 or $250 is submitted alongside on the same one-acre trigger, and it looks at how much impervious cover the finished site will carry. Clearing a house pad, a shop apron, a drive and a drainfield on a few acres reaches one acre of disturbance more easily than most people expect.

Bexar County Public Works, Public Works Permits Verification Guidelines, page 2 items A and B, updated 6 October 2025; Bexar County StormWater Quality Site Development Permit page, bexar.org, rendered 1 September 2026

Two different groundwater authorities, and which one you deal with depends on the aquifer under you
Northern Bexar County over the Trinity sits in the Trinity Glen Rose Groundwater Conservation District, created in 2001 after the state designated the Trinity Aquifer in Bexar County a Priority Groundwater Management Area. Its rules exempt a domestic or livestock well only if the tract is "larger than 10 acres" and the well cannot produce more than 10,000 gallons a day. Below that you need an operating permit, the application fee is $750, and since 16 October 2025 a tract under twenty acres is limited to one well with a verified pump capability set by acreage — 7 gallons per minute under five acres, rising to 17 between fifteen and twenty. The Edwards is a separate authority: the Edwards Aquifer Authority requires every Edwards well to be registered, and treats a well as exempt only if it is incapable of producing more than 25,000 gallons a day, is used solely for domestic or livestock purposes, and does not serve a subdivision requiring platting.

Trinity Glen Rose Groundwater Conservation District Rules as adopted 16 October 2025, rules 1.1, 5.1(a), 5.2 and 6.5(b), and District Fee Schedule adopted 16 November 2023 — trinityglenrose.com/rulesandforms; Edwards Aquifer Authority, Well Registration and Updates, edwardsaquifer.org, rendered 1 September 2026

Also worth knowing before you build in Bexar County

In the ETJ a city can make you plat. Texas courts have held it cannot enforce its building code
San Antonio's extraterritorial jurisdiction is the unincorporated land within five miles of the city boundary that is not in another city's limits or ETJ, and the city publishes a boundary map. Out there the Texas Supreme Court held in 2016 that a general-law city has no ETJ building-code authority, and the Dallas Court of Appeals held in 2018 that a home-rule city does not either, finding that every municipality needs legislative authorisation to enforce building codes beyond its corporate limits and that none exists. Local Government Code sec. 212.049 says the subdivision chapter does not authorise a city to require municipal building permits or enforce its building code in its ETJ. What the city does require out there is real but different: Bexar County's own permit guidance tells applicants in the San Antonio ETJ to get a platting determination or a Certificate of Determination from the city, a storm water review that can end in a fee in lieu of detention, and separate tree, outdoor sign and irrigation permits.

Collin County v. City of McKinney, No. 05-17-00546-CV (Tex. App.—Dallas, 10 May 2018); Town of Lakewood Village v. Bizios, 493 S.W.3d 527 (Tex. 2016); Texas Local Government Code secs. 212.049 and 42.021(a); City of San Antonio Planning Department, Extraterritorial Jurisdiction, sa.gov; Bexar County Public Works Permits Verification Guidelines, page 1, updated 6 October 2025

A county order about your porch light, and the exemption that probably covers your tract
Bexar County regulates outdoor lighting in the unincorporated county within five miles of Camp Bullis, the Lackland Training Annex and Martindale Army Airfield, under an amended court order passed 21 May 2019 that replaced a 2009 order. The authority is Subchapter B of Local Government Code Chapter 240, added in 2007, which lets a commissioners court adopt lighting orders at the request of a base commander. Inside a Military Lighting Region a residence — defined by the order as a single-family, duplex or three-family dwelling — must keep trespass lighting under one and a half foot-candles at the property line, and inside the second region every outdoor light source is capped at 4100K. But the order exempts outdoor lighting for "a tract of land that is maintained as a single-family residence and that is located outside the boundaries of a platted subdivision," and separately exempts agricultural use. So the same house is regulated inside a platted subdivision and exempt on unplatted acreage.

Bexar County Commissioners Court, Amended Order for Regulation of Outdoor Lighting in the Unincorporated Areas of Bexar County, Texas Within 5 Miles of a Military Installation, passed 21 May 2019, secs. (7), (20)(J) and definitions — bexar.org/DocumentCenter/View/38849; Texas Local Government Code ch. 240 subch. B

Most of San Antonio's ETJ cannot be petitioned out of, and the reason is the military
Senate Bill 2038 took effect on 1 September 2023 and lets a resident, or the owners of a majority in value of an area, petition a city to release land from its extraterritorial jurisdiction; San Antonio publishes guidelines and takes petitions at the City Clerk's office. But Local Government Code sec. 42.101 lists areas the route does not reach, and two of them land squarely here: anywhere within five miles of the boundary of a military base at which an active training program is conducted, and — for a city of more than 1.4 million in a county of more than two million — anywhere within fifteen miles of such a base. San Antonio and Bexar County both sit inside those population brackets. Release is also one-way when it does happen: land cannot be put back into an ETJ or annexed without the owner's own request.

Texas Local Government Code secs. 42.101, 42.102, 42.104 and 42.105, rendered from statutes.capitol.texas.gov 1 September 2026; City of San Antonio Planning Department, Extraterritorial Jurisdiction (ETJ) Release Petition Guidelines, sa.gov; U.S. Census Bureau QuickFacts, Bexar County, Texas, Vintage 2025

The floodplain permit is $50, and the freeboard is measured against the worse of two numbers
Every Texas county must keep flood orders to stay in the National Flood Insurance Program, and Bexar County's flood damage prevention court order took effect 19 July 2023 and was amended 22 August 2023. A floodplain development permit is required for any property that is encumbered by, or within 100 feet of, the FEMA 1% annual chance floodplain — a wider trigger than most people assume — and the fee is $50 per activity. The standard is that new construction and substantial improvement of a residential structure must have the lowest floor "elevated to a minimum of one (1) foot above the current effective or ultimate base flood elevation, whichever is greater," with elevation certified by a licensed surveyor, engineer or architect. The county applies Atlas 14 precipitation and its own ultimate-conditions analysis, which is why the second of those two numbers is often the one that binds.

Bexar County Public Works, Floodplain Development Permit Requirements checklist and Floodplain Development Permits page, bexar.org, rendered and read 1 September 2026; Bexar County Flood Damage Prevention Court Order update briefing to Commissioners Court, 1 December 2023

The ground here is two different problems, and the soil named for the county describes one of them
The USDA's Bexar series is type-located in this county, in native pasture off Redland Road north of San Antonio: dark reddish brown cobbly clay loam over cobbly clay, "underlain by hard limestone at depths of 20 to 40 inches," formed in residuum from the Edwards Limestone on the Edwards Plateau. Its two named neighbours make the range plain — Tarrant soils are "skeletal and less than 20 inches thick" over fractured limestone, and Crawford soils are "clayey throughout and have intersecting slickensides." That is the north. South and east of the Balcones Escarpment the county runs into the Blackland Prairie clays, where the Houston Black series carries "high shrink-swell potential and cracks that are 1.3 to 10 cm (1/2 to 4 in) wide" at a foot down. Two feet of soil over rock and a deep swelling clay are different foundation problems and different drainfield problems, and which one you have is a question about your tract, not about the county.

USDA NRCS Official Series Descriptions, BEXAR (rev. 03/2003), TARRANT (rev. 10/2016) and HOUSTON BLACK — soilseries.sc.egov.usda.gov; USDA NRCS description of Major Land Resource Area 86A, Texas Blackland Prairie

The shop bay does not enlarge your drainfield here
TCEQ sizes a septic system on bedroom count or living area, whichever gives the higher figure, and its own application form asks for living area rather than total structure area. That matters on a barndominium, because a four-thousand-square-foot building with eighteen hundred square feet of three-bedroom living space and a twenty-two-hundred-square-foot shop is a 300 gallon-per-day house, not the 375 a whole-footprint reading would give. An authorised agent is free to write a stricter definition and some Texas counties have. Bexar County has not: section 10 of its order is an exhaustive list of its departures from the state rule, lettered A to P, and none of them touches lofts, attached garages or the meaning of living area.

30 Texas Administrative Code ch. 285 Table III and TCEQ form TCEQ-0235; agent stringency under 30 TAC sec. 285.10; Order Adopting Regulations of Bexar County, Texas for On-Site Sewage Facilities, sec. 10

Nothing out here puts a design professional on your house — except the soil
Inside San Antonio, the city's building code chapter requires a registered design professional on a building of 5,000 square feet or more, which two 2,600-square-foot halves under one roof would reach. Nothing equivalent applies to a single-family house in the unincorporated county, because there is no county residential code, no plan review and no permit to attach it to. The one route that still reaches a barndominium is the ground: the Texas Engineering Practice Act removes the private-dwelling exemption for the design of a foundation or slab located on expansive soil, so a tract that tests expansive brings a Texas-licensed engineer into the picture by statute rather than by ordinance. That is a live question in the southern and eastern parts of the county and a different question on the northern limestone, where the problem is depth to rock rather than movement.

Texas Occupations Code sec. 1001.056(c)(2); International Residential Code R403.1.8 referring expansive-soil foundations to International Building Code sec. 1808.6; City of San Antonio Code ch. 10 sec. 10-8(a)(5)

No septic approval, no electricity
The quiet enforcement mechanism in a county with no building inspector is the meter. Bexar County's septic order provides that a release to the City Public Service Board is granted only after an on-site sewage facility has been installed and found compliant, under a Commissioners Court order dating to 13 April 1973 and amended 28 May 1981, and states that "Approval of a subdivision plat is not in itself the grant of a release." The county's own public works answers put it plainly: a temporary meter release for construction is sent to CPS Energy after the septic application is approved, and no meters are released for mobile homes until the system is installed. A building permit application also needs a CPS Energy address verification letter, because CPS Energy is the authorised addressing agent for Bexar County.

Order Adopting Regulations of Bexar County, Texas for On-Site Sewage Facilities, sec. 10 para. P; Bexar County Public Works Frequently Asked Questions, items 5 and 12, bexar.org, rendered 1 September 2026; Bexar County Public Works Permits Verification Guidelines, updated 6 October 2025

1,240 square miles, 2.16 million people, and the land is at the edges
The Census Bureau puts Bexar County at 2,160,088 residents in its 2025 vintage estimate against a 2020 base of 2,009,323 — up 7.5 percent in five years — across 1,240.36 square miles of land. Density was 1,620 people per square mile in 2020, which is a city-county number rather than a rural one, and it is why the acreage question is a question about the ring. San Antonio dominates the middle; the buildable ground is north toward Helotes, Grey Forest and the Bulverde line, west toward Macdona and Lytle, south toward Somerset, Von Ormy and Elmendorf, and east toward Adkins and Saint Hedwig. The rural postcodes with the most Bexar County land in them are 78023, 78264, 78112, 78073 and 78002, and that list is a reasonable map of where a barndominium actually gets built here.

U.S. Census Bureau QuickFacts, Bexar County, Texas, Vintage 2025 estimates; U.S. Census Bureau 2024 Gazetteer county file (land area 1,240.36 sq mi, internal point 29.448671, -98.520147); U.S. Census Bureau 2020 ZCTA-to-county relationship file, tabulated for county GEOID 48029

The county will permit your house if you ask it to — and there are two reasons people do
Bexar County publishes an unusual answer to the residential question. "The County may only conduct a plan review, issue a residential building permit, and issue a subsequent Certificate of Occupancy (Compliance) if the residential plans are submitted for permitting on a voluntary basis. There are two situations where the owner may voluntarily seek a residential building permit: (1) a homeowners association requires the building to be permitted through the Fire Marshal's Office, or (2) a lending institution will require a Certificate of Occupancy (Compliance) from the Authority Having Jurisdiction in order to finalize the loan process." The county also warns that because most unincorporated construction was never permitted, a residential certificate of occupancy simply does not exist for most houses out there, and that it will not inspect a finished building because of the damage that would take. If your lender is going to want that document, it is a question to settle before the slab goes down, not after.

Bexar County Fire Marshal's Office, New Construction FAQs, bexar.org, rendered and read 1 September 2026

An excavator grading a compacted building pad on a cleared lot, with survey stakes and a drainage swale visible.
Below the slab

The expensive surprises are in the ground, not the building

What moves a Texas budget is usually below grade, and it is soil rather than rock: shrink-swell clay. The Blackland Prairie and the Gulf Coast clays move enough between a wet season and a dry one to drive the foundation design across the state's largest markets, which is why several DFW cities require an engineer's seal on the foundation of every new house. Those are the same conditions that decide whether a septic field passes its soil and site evaluation, so the grading plan, the foundation and the drainfield get resolved together rather than one at a time. We price the dirt before we price the building.

What we build in Bexar County

All nine of our services — kits, custom plans, post-frame and steel construction, site preparation, permitting and engineering, through to turnkey builds — are available across Bexar County. What a project costs depends far more on the parcel than on square footage, so we work from your land rather than from a rate card.

See what we build

What a build looks like

Three stages every Bexar County project passes through, from a raw parcel to a finished home. Site work first, because that is where the budget is decided.

Aerial view of an undeveloped rural lot with cleared grass, a live oak and cedar elm treeline, and a pale gravel access track.
Stage one

The parcel

Zoning, setbacks, flood zone and utility access get checked before anything is drawn.

An excavator grading a compacted building pad on a cleared lot, with survey stakes and a drainage swale visible.
Stage two

Pad and permit

Clearing, grading and a compacted pad, while the submittal works through Bexar County.

A finished barndominium at dusk with warm interior lighting glowing through its large windows.
Stage three

Frame to finish

Shell erected and dried in, then systems, insulation and interior finish through to CO.

Those are the rules for Bexar County. Tell us what you want to build and we will draw it to them.

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Where we build around Bexar County

Bexar County and the rural land around it. The buildable acreage for a project this size usually sits outside the city limits, which is frequently what changes who issues your permit.

Our Bexar County service area, covering Bexar County and the surrounding rural acreage. This map marks the territory we serve, not a branch location.

Keep reading

The questions that usually come next once you know what Bexar County allows.

Barndominium Cost Guide

Sourced per-square-foot ranges by tier and by size, with a calculator built on the same figures.

Read it

Is It Legal in Texas?

Classification, zoning, the HOA gate, and why "nonresidential farm building" does not cover a home.

Read it

How Long Does It Take?

Census build-duration data, and what actually sets the permit clock where you are building.

Read it

Nearby areas we build in

Others we cover in this part of Texas. The permitting authority, the adopted design criteria and the zoning can all differ from one to the next.

San Antonio

Bexar County
Comal County

Comal County
Guadalupe County

Guadalupe County
Bandera County

Bandera County

Building in Bexar County: common questions

8 questions we get asked most often about building in Bexar County. If yours is not on the list, ask it directly.

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Do I need a building permit to build a barndominium in unincorporated Bexar County?
No, and Bexar County is unusually clear about why. The county's building-permit authority comes from Local Government Code Chapter 233, Subchapter C — the county fire code, which is open only to counties over 250,000 population — and not from Subchapter F, the residential building code subchapter that a commissioners court has to adopt by order. The Fire Marshal's permit reaches new commercial, publicly accessible and multi-family buildings, and the county's own permit guidance says in terms that it "does not apply to single family residential homes (including duplexes and triplexes)." On the certificate of occupancy question the county writes that unless a permit was sought voluntarily, it "does not have legal authority to regulate residential construction, conduct residential construction inspections, or issue a residential Certificate of Occupancy." There is no zoning in the unincorporated area either. You can ask for a permit voluntarily — the county names two reasons people do, a homeowners association requirement and a lender wanting a certificate of occupancy to close — but nobody will make you.
So is there really nothing regulating a house out there?
No, and this county has more of it than most. The septic permit is real and it is the county's: Bexar County requires every on-site sewage facility in its jurisdiction to be permitted, its order expressly eliminates the ten-acre exemption, and every design has to be prepared and sealed by a Texas professional engineer or registered professional sanitarian. A storm water quality permit costs $500 and is required before you disturb an acre of soil, with a post-construction permit alongside it. A floodplain permit costs $50 and is triggered if your property is encumbered by, or within 100 feet of, the FEMA 1% floodplain. If the Edwards Aquifer recharge or contributing zone crosses your parcel, TCEQ's Edwards rules apply and can require a Water Pollution Abatement Plan. A well is permitted or registered by a groundwater district, not merely drilled. Exterior lighting within five miles of Camp Bullis, the Lackland Training Annex or Martindale Army Airfield is governed by a county court order. A state-licensed plumber is required on new construction regardless. And the recorded restrictions on your own tract are enforceable in a Texas court.
My land is on the Edwards Aquifer recharge zone. What does that actually mean?
It means a state permit can sit on a parcel that has no building code over it, which is the sharpest illustration of how Texas works. TCEQ's Edwards Aquifer rules are at 30 Texas Administrative Code Chapter 213, and both the recharge-zone subchapter and the contributing-zone subchapter are titled for a list of counties that includes Bexar. TCEQ's own guidance for homeowners says construction at a private residence on either zone is subject to those rules, and then gives the ways out. You may not need an individual plan if the lot is larger than five acres with no more than one single-family residence on it, or if impervious cover stays at 20 percent or less of the property — and TCEQ counts rooftops, driveways, concrete pads, sheds and sidewalks as impervious cover. A rainwater harvesting system that puts roof runoff to beneficial use on the property can bring the adjusted figure back under 20 percent. If none of those fits, you file a Water Pollution Abatement Plan on the recharge zone or a Contributing Zone Plan on the contributing zone. One caution on that guidance, because the rule is shaped differently: the recharge-zone exemption at 30 TAC 213.5(h)(2) is the 20 percent impervious cover door alone and has no acreage limb, while the five acres in the regulation is 30 TAC 213.21(b), which reaches a contributing-zone site only where the activity disturbs at least five acres or is part of a larger common plan of development. The practical reading for a metal building with a shop apron and a long drive is that acreage still helps, since 20 percent of five acres is more than 43,000 square feet, but it helps through the impervious cover arithmetic rather than through a separate exemption. Bexar County reinforces it from its own side — its septic application requires a Flood Zone and Edwards Aquifer Recharge Zone certification signed by the engineer or sanitarian. TCEQ's San Antonio regional office covers Bexar on 210-490-3096.
How does septic work here, and how much land do I need?
Bexar County is the TCEQ authorised agent for the entire county except Elmendorf, Hill Country Village, Shavano Park and Hollywood Park, so almost everyone deals with the county. There is no percolation test in Texas — Chapter 285 classifies soil by texture and gives each class a loading rate, and your absorptive area is the daily flow divided by that rate. Sizing keys off bedrooms or living area, whichever gives the higher figure, and the state form asks for living area rather than total structure area, so the shop bay does not count against you. Bexar County has not written a stricter definition of living area into its order, and section 10 of that order is an exhaustive list of its departures. What Bexar does add is significant. Every system must be permitted, with no exemption for a single-family dwelling on ten acres or more. Every design must bear the seal of a professional engineer or registered professional sanitarian; the county will not accept one from anyone else. The minimum is one and a half acres of useable land outside easements and right-of-way dedications on a private well, and half an acre on a central water supply — the state would allow one acre and half an acre respectively. The drainfield must sit 150 feet from a private well. There are three county inspections during installation, the whole installation has to be finished within a week of the first one, and the licence to operate runs five years before it has to be renewed.
Do I need a permit to drill a water well?
Almost certainly something, and which body you deal with depends on which aquifer is under you. Northern Bexar County over the Trinity is in the Trinity Glen Rose Groundwater Conservation District, created after the state designated the Trinity Aquifer in Bexar County a Priority Groundwater Management Area. Its rules exempt a domestic or livestock well only if the tract is larger than ten acres and the well is incapable of producing more than 10,000 gallons a day. Below that threshold the well is non-exempt: it needs an operating permit, the application fee is $750, and since October 2025 a tract under twenty acres is limited to one well whose installed pump capability is verified against an acreage ladder — 7 gallons per minute under five acres, 9 between five and six, and so on up to 17 just under twenty. There are spacing distances from other registered wells and from your own property line, and every permitted well since December 2004 needs a geophysical log. The Edwards is a separate authority: the Edwards Aquifer Authority requires every Edwards well to be registered, and an exempt well must be incapable of producing more than 25,000 gallons a day, used solely for domestic or livestock purposes, and not serving a subdivision requiring platting. The district also enforces the county's one-and-a-half-acre septic minimum in its own rules, so the two constraints stack.
My land is in San Antonio's extraterritorial jurisdiction. Does the city's code apply?
Not the building code, on the authority Texas courts have recognised. San Antonio's ETJ is the unincorporated land within five miles of the city boundary that is not in another city's limits or ETJ, and the city publishes a boundary map. The Texas Supreme Court held in 2016 that a general-law city has no ETJ building-code authority, and the Dallas Court of Appeals held in 2018 that a home-rule city does not either — every municipality needs legislative authorisation to enforce building codes beyond its corporate limits, and none exists. Local Government Code Section 212.049 says the subdivision chapter does not authorise a city to require municipal building permits or enforce its building code out there. What the city genuinely can do is different and still matters. Bexar County's own permit guidance tells applicants in the San Antonio ETJ to obtain a platting determination or Certificate of Determination from the city, a city storm water review that can end in a fee in lieu of detention for new impervious cover, and separate tree, outdoor sign and irrigation permits. Helotes and the other suburban cities carry ETJs of their own, sized by their own populations. The acreage thresholds differ by which side of the line you are on: a division into parts greater than five acres escapes platting in the ETJ, while outside any ETJ the county threshold is lots over ten acres. And read the title commitment, because a recorded development agreement can bind land by consent where regulation cannot.
Can I get my land out of the ETJ?
Often not here, and the reason is the military. Senate Bill 2038 took effect on 1 September 2023 and created a petition route: a resident, or the owners of a majority in value of an area, can petition the city, and the statute says the city shall immediately release. San Antonio publishes guidelines and takes petitions at the City Clerk's office. But Local Government Code Section 42.101 lists areas the route does not reach, and two of them bite hard in Bexar County — anywhere within five miles of the boundary of a military base at which an active training program is conducted, and, for a city of more than 1.4 million population in a county of more than two million, anywhere within fifteen miles of such a base. San Antonio and Bexar County are both inside those brackets, and the county has several active installations. It is also worth knowing what release would and would not change: subdivision regulation would pass to the county rather than disappear, and septic, floodplain, groundwater district and Edwards Aquifer requirements were never city requirements in the first place.
What is the ground like, and will I need an engineer?
It depends which side of the Balcones Escarpment your tract is on, and the answer is genuinely different at the two ends of the county. North of the escarpment you are on the Edwards Plateau. The USDA's Bexar series — type-located in this county, off Redland Road north of San Antonio — is twenty to forty inches of cobbly clay loam and clay over hard limestone. Its neighbour the Tarrant series is skeletal and less than twenty inches thick. That is a rock-excavation problem and a septic problem: a conventional drainfield needs soil depth, and where there is not enough the answer is usually an engineered or aerobic system rather than a trench. It is also karst country — TCEQ's own contractor guidance requires work to stop and the regional office to be notified immediately if a cave, solution cavity or sinkhole turns up during construction. South and east of the escarpment the county runs into Blackland Prairie clay, where the Houston Black series is described as having high shrink-swell potential with cracks half an inch to four inches wide at a foot down. That is where the engineering question changes character: the Texas Engineering Practice Act removes the private-dwelling exemption for the design of a foundation or slab on expansive soil, so a tract that tests expansive brings a Texas-licensed engineer in by statute even though no county inspector will ever look at the result. The parcel-level answer comes from a geotechnical investigation on that tract, not from a county-wide rule.

Building in Bexar County?

Start with the plan. Tell us what you want to build and we will draw it, then confirm what Bexar County will actually let you put on the parcel and what wind load it has to meet. That conversation costs nothing.

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