If you’re considering buying land or building in North Carolina, one of the first terms you may come across is the perc test. Short for “percolation test,” this used to be the old method for checking whether a property’s soil could support a septic system. Today, the process has been replaced by the soil study, a much more accurate and detailed evaluation performed by licensed soil scientists.

For land buyers, developers, and investors, the soil study isn’t just another item on the checklist—it’s often the deciding factor in whether your project can move forward. Without it, you risk purchasing land that can’t legally or safely support development. In other words, a soil study is one of the most important tools you have to protect your investment.

What Is a Perc Test (and Why It’s Outdated)?

A traditional perc test involved digging a hole, filling it with water, and measuring how long it took to drain. If the water absorbed at an acceptable rate, the soil “passed,” meaning it could likely support a septic system. While this approach gave some insight, it was limited. Drainage speed alone doesn’t determine if soil can handle wastewater properly. Factors like the depth to bedrock, seasonal water tables, or restrictive clay layers weren’t fully accounted for. Because of these limitations, North Carolina phased out simple perc tests in favor of more comprehensive soil studies.

What Is a Soil Study?

A soil study (sometimes still called a “perc test” in casual conversation) is now the required process for evaluating whether land is suitable for septic systems. Instead of focusing only on drainage, soil scientists examine multiple conditions that impact long-term system function and safety.

A soil study looks at:

Soil Horizons: How layers of soil differ and whether they can treat wastewater effectively.
Depth to Bedrock or Water Table: Shallow soils may not provide enough filtration.
Soil Texture: Clay-heavy soils may drain poorly, while sandy soils may drain too quickly.
Topography: Slope and elevation affect septic placement and performance.

The results are submitted to the county health department, which determines whether the site qualifies for a standard system, requires an engineered solution, or cannot support septic at all.

For investors, this step provides certainty before money is committed to design, permitting, or construction.

Why Soil Studies Are Essential in North Carolina

Across the Triangle and much of the state, many properties are not served by municipal sewer lines. That means septic systems are the only option. A soil study is the only way to confirm that your land can legally accommodate one.

North Carolina’s soil conditions are highly variable, from sandy soils along river basins to dense clays in the Piedmont. These variations make septic suitability unpredictable. A parcel that looks ideal on the surface could be completely unbuildable once the soil is tested.

By requiring soil studies, North Carolina reduces the risk of septic failures that can pollute groundwater and protect buyers from investing in land that can’t be used as intended. For developers and investors, it’s essentially a pass-or-fail test for the feasibility of your project.

What Happens If Your Land Fails the Soil Study?

A failed soil study doesn’t always mean your land is unusable, but it does mean additional steps will be required—and costs may rise. Options may include:

Engineered Septic Systems: Designed for challenging soils, these can cost more but may allow development to move forward.
Community or Shared Systems: A larger system serving multiple lots in a development.
Connecting to Municipal Sewer: Possible in some locations, though usually expensive and subject to approvals.
Adjusting the Building Plan: Reducing the septic load (such as building fewer bedrooms) may allow conditional approval.

From an investment perspective, knowing about these alternatives early is critical. They can dramatically affect the land’s value and the financial viability of a project.

Preparing for a Soil Study

If you’re considering buying land in North Carolina, here are some steps to prepare for a soil study:

Hire a Licensed Soil Scientist: Choose one familiar with your county’s regulations and soil conditions.
Time It Right: Soil studies are most accurate in spring or fall when conditions aren’t too wet or too dry.
Clear the Area: Make sure the test site is accessible and free of heavy vegetation.
Bring Documentation: Maps, plats, or any prior soil reports can help speed up the process.

Being proactive shows whether your land can support septic and helps you avoid costly surprises later.

The Cost of Skipping a Soil Study

Some buyers are tempted to skip the soil study, especially if they’ve “heard” the land is buildable. That decision can be a costly mistake. Without a soil study, you could end up with:

Land that can’t legally be built on
Higher costs for engineered septic systems
Delays in permitting or construction
Reduced resale value, since future buyers will demand proof of soil approval

For investors and developers, skipping the soil study isn’t just risky—it can be the difference between a profitable project and a loss.

Why Work With Local Experts

Understanding soil studies is one thing; navigating the process in real time is another. Local real estate experts can help you interpret results and connect you with trusted soil scientists and county officials.

At Pickett Sprouse, we guide clients through every stage of land acquisition, from evaluating soil suitability to negotiating contracts with contingencies that protect your investment. Our team understands how soil studies directly impact land value in the Triangle, and we help you anticipate the costs and opportunities before committing.

Conclusion

While many still refer to “perc tests,” the reality in North Carolina is that soil studies are the gold standard. These evaluations go far beyond simple drainage tests, ensuring your land can safely and legally support a septic system. For anyone investing in land, a soil study is not optional—it’s the key to knowing whether your project is even possible.

If you’re considering land in the Triangle or elsewhere in North Carolina, don’t leave your investment to chance. Reach out to Pickett Sprouse, and we’ll help connect you with the right experts and guide you through the process, so you know your land is truly ready for development.