Kendall County
septic services.

Drive the subdivisions spreading out from Boerne and Fair Oaks Ranch, and you’ll spot the tell of Hill Country wastewater: purple-capped sprinkler heads misting treated effluent over limestone-country lawns. Of the 256 septic systems Kendall County authorized in 2024, 177 — nearly seven in ten — were surface-irrigation aerobic units, with raised absorptive mounds a distant second at 65. That ratio isn’t fashion. Rolling Edwards Plateau terrain between 1,000 and 2,000 feet, thin alkaline soils over dolomite and limestone, and rock that starts inches down leave few sites where a conventional buried drainfield can pass a site evaluation.

The water underneath explains the caution above. Kendall County draws almost everything from the Trinity Aquifer — a formation its own groundwater district describes as “tight,” with low porosity, limited fracturing, and modest well yields. The state flagged the problem decades ago: this area was designated a critical groundwater area in 1990 and lies within today’s Hill Country Priority Groundwater Management Area. One clarification worth making, because it gets muddled online: Kendall is not one of TCEQ’s Edwards Aquifer Protection Program counties. The recharge-zone septic rules you’ll read about for Bexar or Comal don’t apply here — what applies is Trinity protection. Kendall is among the Hill Country counties documented as having adopted OSSF rules stricter than the state minimums. 2,348 systems have been permitted here over the last decade, a remarkable number for roughly 50,000 residents, and growth continues to concentrate on the county’s south end, where Boerne (population 19,109 in 2021) meets the San Antonio commute.

Practical upshots for owners: expect an engineered or aerobic design rather than a bargain trench system, keep your maintenance contract current — spray systems don’t forgive neglect — and check regional context if you’re comparing notes across county lines, because Kendall’s ground behaves like Kerr’s, not like the Blackland farm country an hour east. Buying acreage? Site evaluation results will drive your budget more than square footage will; our aerobic systems page covers what those service visits should include.

Permitting is one-stop: the county runs the entire program from Boerne. Requirements and current fees are in the Kendall County permit guide.

Kendall County office: 400 E. Blanco Rd., Boerne — (830) 331-8252, M–F 8–12 and 1–4. Permit walkthrough here.