Soil and perc tests in Iredell County, North Carolina

USDA splits the soil in Iredell County almost evenly between Somewhat limited and Very limited for septic absorption fields. That is 50.8% against 49.2% of the rated acres, a statistical tie. The county calls the site and soil evaluation a perc test. An Environmental Health Specialist evaluates the lot from backhoe pits. USDA NRCS Soil Data Access (SSURGO) · checked 2026-09-11

Somewhat limited or Very limited

USDA rating, a statistical tie

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 Iredell County require one?

Yes. The county calls the site and soil evaluation a perc test. An Environmental Health Specialist evaluates the lot from backhoe pits.

The lot must be cleared of heavy undergrowth, with the footprint of the house staked. Property corners must be marked by a licensed surveyor. A first visit checks that the lot is ready. Then the evaluation is scheduled.

Iredell County Health Department — How to Apply for a Septic Improvement Permit · checked 2026-09-23

How USDA rates the ground in Iredell County

Somewhat limited and Very limited split the county almost evenly. It is a statistical tie, so the county has no single dominant rating. A rating describes the ground, not a parcel. The county's site evaluation decides each lot.

Somewhat limited — 169,902 acres — 50.8% of 334,698 rated acres.
Very limited — 164,796 acres — 49.2% of 334,698 rated acres.
Not rated — 30,970 acres, excluded from the denominator — mostly urban land and water.

Statistical tie: 50.8% vs 49.2% of 334,698 rated acres. That is inside the 2.0-point margin, so this county has no single dominant rating. 30,970 acres unrated. Survey area NC097 version 31, established 2025-09-02.

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 — 324,570 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Slope — 132,457 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Seepage, bottom layer — 64,386 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Depth to bedrock — 35,288 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Depth to saturated zone — 32,337 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Flooding — 31,040 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Filtering capacity — 1,425 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Ponding — 217 acres. Reasons overlap — a component can carry several — so these acres exceed rated acres.
Large stones — 40 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.

ToC2 — Tomlin sandy clay loam, 6 to 10 percent slopes, moderately eroded — 19,298 acres in this county — rated Somewhat limited. Dominant component: Tomlin (90% of the map unit).
ToB2 — Tomlin sandy clay loam, 2 to 6 percent slopes, moderately eroded — 17,831 acres in this county — rated Somewhat limited. Dominant component: Tomlin (90% of the map unit).
CmC2 — Clifford sandy clay loam, 6 to 10 percent slopes, moderately eroded — 16,589 acres in this county — rated Somewhat limited. Dominant component: Clifford (85% of the map unit).
CmB2 — Clifford sandy clay loam, 2 to 6 percent slopes, moderately eroded — 15,833 acres in this county — rated Somewhat limited. Dominant component: Clifford (90% of the map unit).
CgC — Cecil-Urban land complex, 2 to 10 percent slopes — 15,101 acres in this county — rated Somewhat limited. Dominant component: Cecil (55% of the map unit).
FrD2 — Fairview sandy clay loam, 10 to 15 percent slopes, moderately eroded — 14,984 acres in this county — rated Very limited. Dominant component: Fairview (78% of the map unit).
W — Water — 14,738 acres in this county — rated Not rated. Dominant component: Water (100% of the map unit).
CeB2 — Cecil sandy clay loam, 2 to 6 percent slopes, moderately eroded — 14,656 acres in this county — rated Somewhat limited. Dominant component: Cecil (90% 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.

Iredell County — Environmental Health · checked 2026-09-23
Iredell County — Onsite Water Protection · checked 2026-09-23
Iredell County Health Department — How to Apply for a Septic Improvement Permit · 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
Iredell County Health Department — Environmental Health Approved Fees 2025-2026 · 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 county environmental health office, on 704-878-5305.