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What is a Perc Test & How Much Does it Cost?

Find out the basics of perc testing and whether or not you need one for your situation.
Find out the basics of perc testing and whether or not you need one for your situation.

Percolation tests (or simply “perc tests”) are required by many municipalities for the purpose of septic tank installations. 

This test provides important information about the soil’s effectiveness in drainage by measuring water absorption in the ground. Without this crucial data, the septic system could pollute groundwater for neighbors and create big issues for property owners.

So, what is a perc test? We’ll discuss the details and costs associated with perc tests and why you may need one.

What is a Perc Test?

As we mentioned, the purpose of a perc test is to make sure the soil can absorb and filter wastewater from a septic system or other similar disposal system. It’s one of the main ways builders can verify that the property is suitable for installing a septic system or if alternative wastewater treatment methods are necessary.

Here’s the process of perc testing:

  • Digging a hole: The soil expert excavates a hole in the ground at the proposed location of the septic system’s drain field. This hole should be about 2 feet deep and filled with water to saturate the surrounding soil.
  • Measuring the absorption rate: After saturating the soil, the expert measures the rate that the water percolates (or soaks) into the ground by measuring the drop in water level over a specific period, most commonly 60 minutes. The rate of percolation is expressed in minutes per inch or minutes per inch per hour.
  • Interpreting the results: The percolation rate is compared to local regulations to determine whether the soil can effectively handle the disposal of wastewater from a septic system. Different areas may have different requirements for percolation rates based on factors like soil type, groundwater depth, and local environmental regulations.

Slow percolation rates show that the soil may not be able to absorb the wastewater and could lead to health hazards for residents in the area. If this is the case, alternative wastewater treatment may need to be considered.

When Do You Need a Perc Test?

Perc tests aren't always required, but it's important to understand if you need one.
Perc tests aren’t always required, but it’s important to understand if you need one.

Even if you’re not building on raw land or starting a new construction project, you may still need a perc test. Here are the most common situations where you’ll need percolation testing:

Septic System Installation

The septic system is one of the primary functions of residential properties, which means it’s important to follow all regulations to ensure the safety of these systems. 

Local health departments and regulatory agencies require perc tests to determine the soil’s ability to treat wastewater and prevent health hazards or contaminations before installing septic systems.

Property Purchase

Perc tests are also common for new property purchases as part of the due diligence phase of the home buying process. New homeowners must be sure that the property can support a septic system and know its capacity to make an informed decision about their purchase.

Construction Projects

Developers planning to build new housing developments, commercial properties, or other projects in areas without access to public sewer systems must assess the ability to install septic systems.

Using a perc test is one of the most accurate ways to judge whether it’s safe to build on the land and construct a septic system that can function safely for the property.

Importance of Perc Testing in Real Estate

Perc testing plays a key role in real estate home prices and negotiations.
Perc testing plays a key role in real estate home prices and negotiations.

Perc testing is an important part of the real estate industry for several reasons. First, the results of the test can affect property values in different ways. Properties with favorable soil conditions are more attractive to buyers and may allow sellers to command higher prices for their homes.

Additionally, perc tests help buyers to make informed decisions when placing offers and negotiating on properties. If the soil is unsuitable for a septic system or would require expensive modifications, buyers may choose to reconsider their offer and pursue other options.

Who Performs a Perc Test?

These tests can only be performed by trained professionals who can accurately gather and interpret the results.

Perc tests are typically performed by licensed soil scientists, septic tank specialists, or land surveyors with expertise in soil percolation and training on the equipment needed for accurate testing. These experts have the knowledge and understanding to not only conduct the test but also accurately interpret the results.

The qualified professional starts by evaluating the site needed for testing and determining the most suitable location for the perc test. Then they proceed with preparing the test hole, saturating the surrounding soil with water, and measuring the drop in water level over the next 60 minutes.

After the test is complete, the expert will record the data and interpret the results to assess whether the soil’s percolation rate meets local regulations and guidelines for septic tank installation. They prepare the data and results in a formal report and submit it to the local health department as part of the permitting process.

Perc Test Cost

Perc testing costs vary significantly based on your region and local municipality. Some perc testing experts charge hourly for labor, while some counties in the United States have state contractors that charge $300 as a flat rate for perc testing.

However, according to HomeAdvisor, the national average for perc testing is $1,300 in the United States.

The Bottom Line

Perc tests are an important part of real estate and for the safety and well-being of local residents of a community. Failure to accurately conduct perc tests can lead to environmental contamination and health hazards that threaten the health of your fellow neighbors.

While perc testing may seem expensive, they’re essential for buyers to make informed decisions about their home purchases and avoid costly septic tank repairs in the future.

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