Soil and perc tests in Fort Bend County, Texas

What is a perc test and does Fort Bend County require one?

Yes. An engineer or a state-registered site evaluator must do the soil and site evaluation.

Fort Bend County Environmental Health — On-Site Sewage Facility Permits / Packets · checked 2026-10-06

How USDA rates the ground in Fort Bend County

Very limited across most of the county — 97.2% of the rated acres. A rating describes the ground, not a parcel. The county's site evaluation decides each lot.

• Very limited — 473,934 acres — 97.2% of 487,395 rated acres.
• Somewhat limited — 13,344 acres — 2.7% of 487,395 rated acres.
• Not limited — 117 acres — 0.0% of 487,395 rated acres.
• Not rated — 79,632 acres, excluded from the denominator — mostly urban land and water.

97.2% of 487,395 rated acres. 79,632 acres unrated. Survey area TX157 version 23, established 2026-09-03.

USDA NRCS Soil Data Access (SSURGO) · checked 2026-10-06

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 — 474,617 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Depth to saturated zone — 237,479 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Flooding — 170,876 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Ponding — 23,173 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Seepage, bottom layer — 12,497 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Slope — 4,621 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
• Filtering capacity — 1,075 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.

• La — Lake Charles clay, 0 to 1 percent slopes — 128,945 acres in this county — rated Very limited. Dominant component: Lake Charles (90% of the map unit).
• Ea — Edna loam, 0 to 1 percent slopes — 75,233 acres in this county — rated Very limited. Dominant component: Edna (87% of the map unit).
• Ma — Brazoria clay, 0 to 1 percent slopes, rarely flooded — 63,815 acres in this county — rated Very limited. Dominant component: Brazoria (90% of the map unit).
• Be — Bernard-Edna complex, 0 to 1 percent slopes — 59,408 acres in this county — rated Very limited. Dominant component: Bernard (60% of the map unit).
• Pa — Pledger clay, 0 to 1 percent slopes, rarely flooded — 25,866 acres in this county — rated Very limited. Dominant component: Pledger (85% of the map unit).
• Bb — Bernard clay loam, 0 to 1 percent slopes — 22,436 acres in this county — rated Very limited. Dominant component: Bernard (90% of the map unit).
• Nc — Norwood loam, 0 to 1 percent slopes, rarely flooded — 18,558 acres in this county — rated Very limited. Dominant component: Norwood (90% of the map unit).
• KauA — Katy-Urban land complex, 0 to 1 percent slopes — 17,645 acres in this county — rated Very limited. Dominant component: Katy (55% of the map unit).

USDA NRCS Soil Data Access (SSURGO) · checked 2026-10-06

Sources

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

1. Fort Bend County Environmental Health — On-Site Sewage Facility (OSSF) Program · checked 2026-10-06
2. Fort Bend County Environmental Health — Procedures on Applying for an OSSF Permit · checked 2026-10-06
3. Fort Bend County Environmental Health — OSSF fee schedule letter to Commissioners Court · checked 2026-10-06
4. Order Adopting Rules of Fort Bend County, Texas for On-Site Sewage Facilities, Section 10(a) · checked 2026-10-06
5. Fort Bend County Environmental Health — On-Site Sewage Facility Permits / Packets · checked 2026-10-06
6. Fort Bend County Environmental Health — Permit/Inspection Fees · checked 2026-10-06
7. 30 TAC §285.91(2), Table II -- Septic Tank and Aerobic Treatment Unit Sizing · checked 2026-09-23
8. USDA NRCS Soil Data Access (SSURGO) · checked 2026-10-06

Related pages

• Septic rules and requirements in Fort Bend County, Texas
• Septic permits and fees in Fort Bend County, Texas
• Septic rules and requirements in Texas
• Septic rules in Fort Bend County