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Soil and perc tests in Wake County, North Carolina

USDA rates most of the soil in Wake County Very limited for septic absorption fields — 64.6% of the rated acres. No USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-23

Very limited

USDA rating, 64.6% of rated acres

checked 2026-09-23

Slow water movement

Most common limiting reason

checked 2026-09-23

Yes

Site evaluation required

checked 2026-09-23

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

No

The county investigates the site instead. It looks at slope, landscape and soil layers before it decides.

N.C. Department of Health and Human Services — On-Site Water Protection · checked 2026-09-23

How USDA rates the ground in Wake County

Very limited across most of the county — 64.6% of the rated acres. A rating describes the ground, not a parcel. The county's site evaluation decides each lot.

  • Very limited — 288,347 acres — 64.6% of 446,548 rated acres.
  • Somewhat limited — 158,201 acres — 35.4% of 446,548 rated acres.
  • Not rated — 101,939 acres, excluded from the denominator — mostly urban land and water.

64.6% of 446,548 rated acres. 101,939 acres unrated. Survey area NC183 version 27, established 2025-08-27.

USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-23

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 — 414,300 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
  • Depth to saturated zone — 173,952 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
  • Slope — 142,257 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
  • Seepage, bottom layer — 111,090 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
  • Depth to bedrock — 73,868 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
  • Flooding — 56,238 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
  • Filtering capacity — 5,884 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
  • Ponding — 535 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.

  • ChA — Chewacla and Wehadkee soils, 0 to 2 percent slopes, frequently flooded — 42,556 acres in this county — rated Very limited. Dominant component: Chewacla (50% of the map unit).
  • Ur — Urban land — 40,420 acres in this county — rated Not rated. Dominant component: Urban land (100% of the map unit).
  • RgC — Rawlings-Rion complex, 6 to 10 percent slopes — 27,989 acres in this county — rated Somewhat limited. Dominant component: Rawlings (55% of the map unit).
  • CfC — Cecil-Urban land complex, 2 to 10 percent slopes — 23,399 acres in this county — rated Somewhat limited. Dominant component: Cecil (55% of the map unit).
  • PaD — Pacolet sandy loam, 10 to 15 percent slopes — 22,221 acres in this county — rated Somewhat limited. Dominant component: Pacolet (85% of the map unit).
  • CrD — Creedmoor-Green Level complex, 10 to 15 percent slopes — 21,709 acres in this county — rated Very limited. Dominant component: Creedmoor (60% of the map unit).
  • RgD — Rawlings-Rion complex, 10 to 15 percent slopes — 21,105 acres in this county — rated Somewhat limited. Dominant component: Rawlings (55% of the map unit).
  • BcC — Beltline-Urban land-Cecil complex, 2 to 10 percent slopes — 19,918 acres in this county — rated Very limited. Dominant component: Beltline (40% of the map unit).

USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-23

Sources

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

  1. Wake County Government — Onsite Water Protection · checked 2026-09-23
  2. Wake County Government — Wastewater Fees · checked 2026-09-23
  3. Wake County Government — Septic System Permitting FAQs · checked 2026-09-23
  4. N.C. Department of Health and Human Services — On-Site Water Protection · checked 2026-09-23
  5. Wake County Government — Finding an Existing Wastewater Permit · checked 2026-09-23
  6. USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-23

Verify before you act. Septic rules are set locally and they change. Check anything here before you spend money on it. Call the Wake County Onsite Water Protection Division, on 919-856-5700.

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