Blanco County Septic Permits (2026): Process & Rules

A septic permit for a single-family home in Blanco County costs $300, or $375 where a licensed professional designs the system, plus a $40 or $60 filing fee paid to the County Clerk. Permits go through the county OSSF Inspector in Johnson City on the county’s own application packet, and come with an unusual deadline: the permit is valid for one year, and all fees are non-refundable. The fee schedule is printed inside that packet rather than on a page of its own, which is why these amounts are hard to find; it carries an effective date of October 2025.

Who Issues Septic Permits in Blanco County?

The Blanco County Authorized Agent’s jurisdiction is the entire county except Johnson City and Round Mountain. Inside those two towns, the municipal programs take over.

Blanco County OSSF Inspector P.O. Box 471, Johnson City, TX 78636 Phone: (830) 868-2117 Email: Inspector@co.blanco.tx.us Jurisdiction: unincorporated Blanco County (TCEQ agent #620016)

That carve-out is the first thing to check: much of the area on the edge of Johnson City may answer to city hall, not the county. TCEQ’s On-Site Activity Reporting System (OARS) is the authoritative “who-permits-where” lookup for ambiguous parcels. Everything below describes the county program.

What Does a Blanco County Septic Permit Cost?

$300 for a single-family residence, $375 if the system needs a licensed professional design, and $450 for commercial or recreational. The schedule is headed “Blanco County Fee Schedule, Effective October, 2025” and sits inside the OSSF application packet, a few pages past the application itself.

Two things about the filing fee catch people out. It is a separate check, made out to the Blanco County Clerk, not to the county’s OSSF program. And it is due before the license to operate is issued, not with the application, so it lands at the end of the project rather than the start. Commercial designs are charged by size instead: $20 for the first page and $4 for each additional page.

The schedule does not mention the $10 state fee that Texas Health and Safety Code Chapter 367 attaches to every septic permit, so ask the Inspector’s office whether the $300 is before or after it.

The Local Rules That Shape Your Application

Three county requirements do most of the work here: a five-acre minimum for septic-plus-well on land platted after 1998, a 1,000-gallon minimum tank, and one-year permit validity.

The five-acre rule is the one that surprises land buyers. If your tract was platted after 1998 and you need both a well and a septic system (which, in unincorporated Blanco County, you almost certainly do), the county requires at least 5 acres. Older plats escape it, which quietly makes pre-1998 lots more buildable than they look on paper. (This is a county overlay on top of the state’s separate 10-acre permitting exemption: different rule, different acreage, different effect; don’t let a seller conflate them.)

The one-year validity turns sequencing into strategy: don’t file until your builder’s timeline is real. A permit that expires before construction requires re-filing and re-payment, and every fee is non-refundable under county policy.

The 1,000-gallon floor mostly matters for small builds: cabins and guest houses that might size smaller elsewhere in Texas size up here.

How the Process Runs

Site evaluation → design → county application packet → review → permit to construct → build and inspect, with licensed professionals required at each technical step.

1. Site evaluation. A TCEQ-licensed Site Evaluator or professional engineer profiles your soil. On Blanco’s thin limestone uplands, this step usually settles the system type: local designers report aerobic spray as the default where soil depth runs short, aerobic drip on tight or steep sites, and conventional only in deeper-soil pockets.
2. Design. Your designer prepares planning materials to 30 TAC Chapter 285 standards plus the county’s requirements. Aerobic designs carry the maintenance-contract obligations that follow the system for life.
3. Application. File the county’s OSSF application and checklist (the October 2025 revision is current) with the permit fee from the schedule above. The packet includes an entry-authorization for county inspection of the property, and an affidavit step with its own $21 filing fee where one is required.
4. Review. Local professionals report typical turnaround times of two to four weeks depending on the queue; the county doesn’t publish an official average.
5. Permit to construct, then build. Construction must be inspected before cover-up, and the one-year clock means the entire sequence (from permit through final inspection) must fit within a single building season.

Which Professionals You’ll Need

A licensed Site Evaluator (or PE) for the soil work, an Installer II for anything aerobic, and, for aerobic systems, a licensed Maintenance Provider under contract from day one. Verify every license by name in TCEQ’s records search (www2.tceq.texas.gov/lic_dpa/index.cfm). Blanco County’s working ecosystem includes registered sanitarians and site evaluators who handle design-through-permit as a package; a designer who already knows the Inspector’s checklist tends to clear review on the first pass, which is worth real money against a one-year permit clock.

Official Documents

• Blanco County OSSF Application & Checklist (Oct 1, 2025 revision): county website, Environmental/OSSF pages
• Blanco County Fee Schedule, “Effective October, 2025” — printed inside the same packet
• 30 TAC Chapter 285: the state standards your design is reviewed against
• TCEQ OARS: jurisdiction lookup for parcels near Johnson City or Round Mountain

Blanco County Permit FAQs

How much does a septic permit cost in Blanco County?

$300 for a single-family residence, $375 if a licensed professional designs the system, $450 commercial, plus a $40 or $60 filing fee to the County Clerk. Those come from the “Blanco County Fee Schedule, Effective October, 2025”, printed inside the OSSF application packet. Every fee is non-refundable, and the permit lasts a year, so a permit taken out too early is money spent twice. The Inspector’s office confirms current figures at (830) 868-2117.

Do I need five acres to build in Blanco County?

Only if your land was platted after 1998 and needs both a well and a septic system, then the county’s five-acre minimum applies; older plats are exempt. This is the county’s density rule, separate from the state’s 10-acre permitting exemption.

How long does a Blanco County septic permit last?

One year. If it lapses before your system is built and inspected, you’re refiling and repaying. File when construction is genuinely imminent, not when the land closes.

What system will my land require?

On most of the county’s thin limestone soils, expect an aerobic system (spray where the site allows, drip where it’s tight), with conventional reserved for deeper-soil pockets; the licensed site evaluation decides, not preference. Budget accordingly: aerobic costs run roughly double those of conventional systems, plus the required maintenance contract.

Back to the Blanco County septic hub for ground conditions and licensed providers.