Soil and perc tests in Denton County, Texas

USDA rates most of the soil in Denton County Very limited for septic absorption fields — 90.2% of the rated acres. Texas requires a site evaluation before Denton County issues a permit. USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-22

Very limited

USDA rating, 90.2% of rated acres

checked 2026-09-22

Slow water movement

Most common limiting reason

checked 2026-09-22

Yes

Site evaluation required

checked 2026-09-23

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

Yes. Texas requires a site evaluation before Denton County issues a permit.

A licensed engineer or a registered sanitarian evaluates the soil and the site. Denton County requires this check before it will size a system.

Texas Administrative Code, Title 30, Chapter 285, Section 285.30, Site Evaluation · checked 2026-09-23

How USDA rates the ground in Denton County

Very limited across most of the county — 90.2% of the rated acres. A rating describes the ground, not a parcel. The county's site evaluation decides each lot.

Very limited — 470,682 acres — 90.2% of 522,011 rated acres.
Somewhat limited — 51,329 acres — 9.8% of 522,011 rated acres.
Not rated — 91,148 acres, excluded from the denominator — mostly urban land and water.

90.2% of 522,011 rated acres. 91,148 acres unrated. Survey area TX121 version 22, established 2025-09-04.

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.

Slow water movement — 492,997 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Depth to bedrock — 129,577 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Flooding — 63,657 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Slope — 40,251 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Seepage, bottom layer — 10,190 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Depth to saturated zone — 7,681 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Filtering capacity — 7,228 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.

67 — Sanger clay, 1 to 3 percent slopes — 52,313 acres in this county — rated Very limited. Dominant component: Sanger (90% of the map unit).
W — Water — 46,233 acres in this county — rated Not rated. Dominant component: Water (100% of the map unit).
75 — Somervell gravelly loam, 1 to 5 percent slopes — 32,624 acres in this county — rated Very limited. Dominant component: Somervell (100% of the map unit).
74 — Slidell clay, 1 to 3 percent slopes — 29,948 acres in this county — rated Very limited. Dominant component: Slidell (85% of the map unit).
66 — Ponder loam, 1 to 3 percent slopes — 23,609 acres in this county — rated Very limited. Dominant component: Ponder (100% of the map unit).
35 — Gasil fine sandy loam, 1 to 3 percent slopes — 20,361 acres in this county — rated Somewhat limited. Dominant component: Gasil (85% of the map unit).
23 — Callisburg fine sandy loam, 1 to 3 percent slopes — 20,270 acres in this county — rated Very limited. Dominant component: Callisburg (100% of the map unit).
13 — Birome-Rayex-Aubrey complex, 2 to 15 percent slopes — 19,233 acres in this county — rated Very limited. Dominant component: Birome (33% 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.

Denton County, Texas — Environmental Health Division · checked 2026-09-23
Denton County Subdivision Rules and Regulations (July 2009), Section IV(C) · checked 2026-09-23
Denton County Public Health — What You Must Know: On-Site Sewage Facilities (OSSF) · checked 2026-09-23
Texas Administrative Code, Title 30, Chapter 285, Section 285.30, Site Evaluation · 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 Denton County Public Health, Environmental Health Division, on 940-349-2920.