Soil and perc tests in Johnston County, North Carolina

USDA rates most of the soil in Johnston County Very limited for septic absorption fields — 64.3% of the rated acres. An Environmental Health Specialist evaluates the site and the soil. The permit is issued or denied on that evaluation. USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-11

Very limited

USDA rating, 64.3% of rated acres

checked 2026-09-11

Slow water movement

Most common limiting reason

checked 2026-09-11

Yes

Site evaluation required

checked 2026-09-23

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

Yes. An Environmental Health Specialist evaluates the site and the soil. The permit is issued or denied on that evaluation.

North Carolina evaluates the soil and the site. It does not run a percolation test. Before the visit, stake the area to be evaluated and the structure. If the lot passes, a survey and a plat may be required before the permit is filed.

Johnston County Environmental Health — On-Site Wastewater (Septic Systems) · checked 2026-09-23

How USDA rates the ground in Johnston County

Very limited across most of the county — 64.3% of the rated acres. A rating describes the ground, not a parcel. The county's site evaluation decides each lot.

Very limited — 295,497 acres — 64.3% of 459,441 rated acres.
Somewhat limited — 163,944 acres — 35.7% of 459,441 rated acres.
Not rated — 6,432 acres, excluded from the denominator — mostly urban land and water.

64.3% of 459,441 rated acres. 6,432 acres unrated. Survey area NC101 version 30, established 2025-08-27.

USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-11

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 — 429,251 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Depth to saturated zone — 346,173 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Flooding — 91,139 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Seepage, bottom layer — 86,893 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Slope — 54,661 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Ponding — 17,101 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Depth to bedrock — 14,221 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Filtering capacity — 2,059 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.

Ra — Rains sandy loam, 0 to 2 percent slopes — 36,499 acres in this county — rated Very limited. Dominant component: Rains (58% of the map unit).
NoA — Norfolk loamy sand, 0 to 2 percent slopes — 32,946 acres in this county — rated Somewhat limited. Dominant component: Norfolk (83% of the map unit).
GoA — Goldsboro sandy loam, 0 to 2 percent slopes — 30,988 acres in this county — rated Very limited. Dominant component: Goldsboro (90% of the map unit).
GeB — Gilead sandy loam, 2 to 8 percent slopes — 30,133 acres in this county — rated Very limited. Dominant component: Gilead (80% of the map unit).
Bb — Bibb sandy loam, 0 to 2 percent slopes, frequently flooded — 28,749 acres in this county — rated Very limited. Dominant component: Bibb (80% of the map unit).
NoB — Norfolk loamy sand, 2 to 6 percent slopes — 26,116 acres in this county — rated Somewhat limited. Dominant component: Norfolk (83% of the map unit).
Wt — Wehadkee loam, 0 to 2 percent slopes, frequently flooded — 20,535 acres in this county — rated Very limited. Dominant component: Wehadkee (85% of the map unit).
GeD — Gilead sandy loam, 8 to 15 percent slopes — 18,605 acres in this county — rated Very limited. Dominant component: Gilead (80% of the map unit).

USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-11

Sources

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

Johnston County Environmental Health — On-Site Wastewater (Septic Systems) · checked 2026-09-23
Johnston County Environmental Health Fee Schedule · checked 2026-09-23
15A NCAC 18E .0801, Septic Tank Capacity Requirements · checked 2026-09-23
USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-11

Verify before you act. Septic rules are set locally and they change. Check anything here before you spend money on it. Call the Johnston County Environmental Health Department, on 919-989-5180.