Soil and perc tests in Travis County, Texas

USDA rates most of the soil in Travis County Very limited for septic absorption fields — 95.8% of the rated acres. Travis County requires a site and soil evaluation before it issues a permit. It calls for profile holes and a soil analysis report. USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-22

Very limited

USDA rating, 95.8% of rated acres

checked 2026-09-22

Depth to bedrock

Most common limiting reason

checked 2026-09-22

Yes

Site evaluation required

checked 2026-09-23

What is a perc test and does Travis County require one?

Yes. Travis County requires a site and soil evaluation before it issues a permit. It calls for profile holes and a soil analysis report.

The evaluation tells the county what system the lot can support.

Travis County Code, Chapter 448, Rules of Travis County, Texas for On-Site Sewage Facilities, §448.035 · checked 2026-09-23

How USDA rates the ground in Travis County

Very limited across most of the county — 95.8% of the rated acres. A rating describes the ground, not a parcel. The county's site evaluation decides each lot.

Very limited — 528,733 acres — 95.8% of 552,087 rated acres.
Somewhat limited — 20,881 acres — 3.8% of 552,087 rated acres.
Not limited — 2,473 acres — 0.4% of 552,087 rated acres.
Not rated — 103,498 acres, excluded from the denominator — mostly urban land and water.

95.8% of 552,087 rated acres. 103,498 acres unrated. Survey area TX453 version 27, established 2025-09-05.

USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-22

What limits absorption here

The reasons USDA gives for the rating, by the acres they affect. A component can carry several, so the acres overlap.

Depth to bedrock — 325,423 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Slow water movement — 269,115 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Slope — 127,495 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Large stones — 68,740 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Flooding — 48,350 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Seepage, bottom layer — 28,752 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Filtering capacity — 23,834 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Depth to saturated zone — 2,093 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Ponding — 83 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.

Ratings by soil map unit

The largest map units in the county, each with its rating. A soil survey names the ground. The county's evaluation of your lot is what a permit turns on.

BlD — Brackett-Rock outcrop complex, 1 to 12 percent slopes — 110,018 acres in this county — rated Very limited. Dominant component: Brackett (68% of the map unit).
HnB — Houston Black clay, 1 to 3 percent slopes — 71,307 acres in this county — rated Very limited. Dominant component: Houston Black (80% of the map unit).
BoF — Brackett-Rock outcrop-Real complex, 8 to 30 percent slopes — 57,011 acres in this county — rated Very limited. Dominant component: Brackett (38% of the map unit).
TaD — Eckrant very stony clay, 5 to 18 percent slopes — 34,872 acres in this county — rated Very limited. Dominant component: Eckrant (90% of the map unit).
TcA — Eckrant and Speck soils, 0 to 2 percent slopes — 25,727 acres in this county — rated Very limited. Dominant component: Eckrant (63% of the map unit).
HnC2 — Houston Black clay, 3 to 5 percent slopes, moderately eroded — 22,509 acres in this county — rated Very limited. Dominant component: Houston Black (90% of the map unit).
VoD — Volente silty clay loam, 1 to 8 percent slopes — 20,002 acres in this county — rated Very limited. Dominant component: Volente (75% of the map unit).
W — Water — 19,708 acres in this county — rated Not rated. Dominant component: Water (100% of the map unit).

USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-22

Sources

Each figure on this page has a government source and a checked-on date.

Travis County TNR — On-Site Sewage Facility (Septic System) Permit · checked 2026-09-23
Travis County Code, Chapter 448, Rules of Travis County, Texas for On-Site Sewage Facilities, §448.032(b) · checked 2026-09-23
Travis County Transportation and Natural Resources — FY2026 Development Related Fees Schedule · checked 2026-09-23
Texas Administrative Code, Title 30, Chapter 285, §285.91(12), Table II · checked 2026-09-23
USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-22

Verify before you act. Septic rules are set locally and they change. Check anything here before you spend money on it. Call the county environmental health office, on (512) 854-4215.