How Much Does A Perc Test Cost?

Nick Durante
by Nick Durante

When you own land, there are so many tests and evaluations that need to be done, that some of them can get lost in the mix. One such often overlooked important test for homeowners is the percolation test, or perc test, and it is quite important. Perc tests are done by drilling a hole into the soil and filling it with water to determine the absorption of the soil.

The average perc test cost is $700 for a standard test with 2 holes. Homeowners spend an average of $1,750 for perc testing a large yard due to additional labor at $150 per hour. Excavation costs another $250 per hour and can take up to 4 hours if they cannot drill a hole into the soil and need to dig.

Let’s get into the importance of perc tests, how the cost is determined, and why it matters.

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What is the Purpose of a Perc Test?

The purpose of a perc test is to determine the absorption of water in soil and how quickly it passes through. Perc tests are of the utmost importance because they can indicate how you will need to proceed with a septic system if you lack access to a municipal sewer system. Perc tests are mandated by health departments and must be done before septic tank and setup is installed on your property.

For many landowners, the results of a perc test can also provide useful information about what can grow on the land. If you have plants that require a lot of moisture that are struggling to survive, your perc test may indicate that water is absorbing quickly and that would explain it. That aspect of perc tests is not why they are mandated but knowing the soil drainage rate can help determine what you can grow.

How Much Does it Cost to Get a Perc Test?

Landowners spend between $600 and $800 on average for a perc test. However, the cost of perc tests varies largely based on who you hire for the job. The range of costs for perc tests spans between $300 and $1,200 in many cases.

If your septic contractor does not have to do more than dig a hole 6” to 1’ wide with a shovel, your perc test will cost closer to $300-$600. Once you get into large excavations using a backhoe or other machinery, perc tests cost between $600 and $1,200 or more. As with anything related to being a homeowner and builder, labor is what makes up the majority of perc test costs.

Large scale perc tests involving excavation can cost you $100-$200 per hour, and sometimes that rate applies to each soil scientist or septic contractor involved. Depending on the size amount of prep work needed, the actual perc test labor itself usually adds up to 4-6 hours.

Small scale, simple perc tests, however, cost $300-$600 and usually only involve a septic contractor. That is because no engineer or soil scientist involved, reducing labor.

Who Does a Perc Test?

Perc tests are conducted by septic contractors, but some places require that soil scientists and other specialists be involved. The very first thing that you should do is reach out to your local health department about perc tests. Your local health department can tell you about several important factors regarding your upcoming perc test, such as:

  • How many holes they require to be drilled/dug
  • Hole dimensions
  • What kind of professionals they require on-site during perc test
  • Optimal month/months for perc testing

Each health department is different, and some may say that a septic contractor is not enough for a perc test. If that is the case, they may require a soil scientist, engineer, and possibly even a local health official to be present for the perc test.

Once you have this information, you can proceed by contacting a local septic contractor. In some cases, however, once you’ve contacted your health department and paid fees, they will take care of contacting a contractor for you.

Perc Test Costs

There are many factors involved in the overall cost of a perc test. In general, the simpler the perc test and excavation requirements, the lower the cost of the perc test will be.


The dimensions of the holes that are drilled to complete a perc test play into the cost. However, that is only really the case in the event that large holes need to be dug. If a hole cannot be drilled or a shovel can’t be used, an excavator will be brought in.

Once you get into excavation, expect to spend an extra $200-$300 minimum. The excavation cost is reflected in labor costs, as bringing in an excavator operator can cost $200-$300 per hour. Luckily, backhoe excavations typically do not take long, so it usually adds 1-3 hours of labor.

Otherwise, there is no correlation between hole size and price without the added labor costs.

Lot Size

How big is the lot that requires a perc test? Today, the majority of municipalities require that perc tests be conducted with a minimum of 2 holes. However, bigger lots may jump up to 3-5 holes, or even more, to increase accuracy of the perc test.

That is because a distance of 40 feet is required between holes typically. Larger land with enough room to space multiple holes 40 feet apart will give extremely accurate perc test results and may be required. However, the more holes drilled, the higher the cost of a perc test can be.

Because of that, lot size directly affects the cost of a perc test, mostly in labor as more holes means more time spent drilling.

Soil Condition

What kind of condition is your soil in? If your soil is sandier in quality, it will be reflected in a fast absorption rate. If your soil is in bad condition and contains lots of sediment or clay, water will drain slowly through it.

Not only that, but hard, tough soil means that excavation will be tougher and can include more laborers. Many times, septic contractors will decide that a backhoe needs to be brought in when soil contains lots of sediment or clay.

Number of Laborers

The number of laborers required to complete a perc test ultimately determines the price more than anything. For the most part, you can tell that your perc test will require many laborers based on the following factors:

  • The soil is tough, and contains sediment or clay
  • Multiple holes need to be drilled/dug
  • Your municipality requires an engineer/soil scientist be present
  • A backhoe operator is required

Some municipalities are stricter than others and may require more personnel be on site for a perc test. If that is the case, those personnel typically include a soil scientist, an engineer, and a septic contractor. With each of those people at a $100-$200 hourly rate and 4 hours of work, for example, that could cost $1,200-$2,400 if 3 or more workers are involved. If the holes are hand-dug, however, and 1-2 people are present, it averages $700 total for a perc test.

Perc Testing Land

The terrain of the land affects perc testing greatly. Unfortunately, some land is easier to conduct a perc test on than others. Terrain not only affects the drainage capabilities of the soil, but also the ease of access for laborers.

Most importantly, though, there are several land factors involved in installing septic systems. After all, the purpose of a perc test is to figure out the logistics of a septic system for the land. There are several land factors that affect perc testing and septic systems, such as:

  • What kind of soil the land is filled with
  • The slope of the land (20%-30% incline allowed)
  • No wetlands or flood zones
  • The potential drain field won’t be impacted by storm runoff path

So long as your land meets the above requirements and passes a perc test, it should qualify for a septic system.

How is a Septic Perc Test Done?

Simply put, a septic perc test is done by drilling a hole, filling it with water, and observing the soil absorption rate. When a contractor or engineer creates this hole, they are looking out for a few things, including:

  • Sediment and rocks
  • Clay-like soil
  • Water tables
  • Soil drainage abilities

When doing a deep hole test as a part of a septic perk test, a 2-3 ft. or 7-10 ft. hole is drilled or dug. As they go deeper drilling the hole, any resistance caused by rock or clay can indicate that the test may be a failure. However, a little bit of clay or rock does not always mean that your land won’t pass a perc test.

The water table refers to the top layer of the subsurface of the ground that retains water. Sometimes, the water levels vary from season to season, and the presence of water does not mean failure always. However, if there is a significant amount of water retention, some sort of de-watering is in order.

The perc test process is broken up into a few steps.

1. Drilling or Digging the Holes

The more holes dug or drilled, the more accurate the perc test results will be. Creating the holes is the first step of a perc test and is often done with a shovel. The minimum number of holes is based on the regulations of your municipality.

Once the hole is dug, the contractor or engineer removes loose soil from the bottom of the hole. After the loose soil is taken out, the contractor will place 2”-4” of gravel at the bottom of the hole.

2. Pre-soak and Soak

Before actually pouring a good amount of water down the hole, workers will lightly pre-soak the holes. This is done using a small amount of water lightly sprayed or poured into the hole to recreate the conditions of a septic system.

After 2-3 hours of pre-soaking, a steady flow of water is poured into the hole over the course of 4 hours. This process is important, as they need to maintain a 12” water level in the hole throughout the entire 4 hours by continually adding more.

After the 4 hours are up, the professionals will leave the holes as is until the following day.

3. Day 2

The contractor will look in the dug holes and carefully clean out any weak, loose soil. From there, they will add more water to the hole until it sits 6” above the gravel at the bottom of the hole. After that, the workers will observe the absorption over the course of 30 minutes.

How slowly or quickly the water falls until reaching the gravel factors into their calculations for percolation. The way that percolation rate is determined is by how many minutes it took to drain per inch of water. Depending on where you live, the cutoff range for percolation rate per inch ranges from 30 minutes to 2 hours.

If it only takes 2 or 3 minutes per inch to drain, that indicates that the soil is draining too fast. Just as too slow of drainage can lead to a perc test failure, so can fast drainage.

How Long is a Perc Test Valid For?

Perc test results are valid for 2-5 years. That time frame varies depending on the rules and regulations in your locality. When the time comes for you to get another perc test, the local health department will decide if and when another perc test will be conducted.

Typically, the local health department will look at the last perc test and decide how soon a perc test will be needed, if at all.

What Does a Failed Perc Test Mean?

Unfortunately, if your land fails a perc test, that means that you cannot feasibly build a house there. Failed perc tests often occur in rural areas separated from municipal sewer systems. Failing a perc test can save you a lot of heartache in money if you make the land purchase contingent on the results.

In other words, many wise, prospect landowners will negotiate a land purchase and establish that the deal won’t go through unless it passes a perc test. Areas that contain lots of homes and are well developed rarely have failed perc tests. Once you get into rural, disconnected areas with soil containing sediment, a PERC test failure is common.

The testing standards are dependent on local codes and requirements, so failure is determined by municipality as much as the soil itself. A failed perc test indicates that the land does not qualify as a safe dwelling space. It is better to know that land does not have suitable soil drainage before purchasing it than getting stuck with a lemon, so to speak.

What Can Be Done About a Failed Perc Test?

Usually, landowners take steps to de-water the land. The drainage site needs to have water directed away from it through the use of pipes and trenches beneath the surface. To have your drainage site de-watered, you need to get in touch with a contractor.

De-watering is a temporary process and can cost between $1,000 and $4,000. The process ranges in cost based on how many people are involved, i.e. a contractor or civil engineer. It is well worth the cost of de-watering when it results in you being able to pass the next perc test and make the land livable.

FAQs About Perc Tests

What is the average hole dimensions for perc tests?

It varies, but the dimensions are usually required to be 2’-3’ deep, and 6”-12” wide. However, if backhoe excavation is required, the hole could be as wide as 3’ or more.

If you want to expand your home, will a perc test or inspection need to be done?

Depending on local codes and the type of expansion, yes, at least an inspection will need to be done. This is particularly true if you are significantly increasing your home’s size or adding bathrooms to it.

Is there any way to save money on the cost of a perc test?

Unfortunately, there are no shortcuts around paying full price for a perc test. With that said, if the land that you are looking at is small, has absorbent soil, and drains well, it will save you money on your perc test. Additionally, if you live somewhere with less strict of perc test standards that allows for a sole contractor to be involved, it will save you money on labor.

Do You Need Soil Testing Services?

Get free, zero-commitment quotes from pro contractors near you.

What Did We Learn?

Perc tests range in cost between $300 and $1,200 but average a span of $600-$800. If your land requires a backhoe excavation to conduct a perc test, it can easily add $200-$300 to the total of the perc test. Septic contractors perform perc tests, and they sometimes include an excavator, soil scientist, or engineer.

Your best bet is to make your land purchase contingent on the passing of a perc test before making a final decision. Failure to pass a perc test means work will need to be done to make the land livable. Good luck passing your perc test!

Nick Durante
Nick Durante

Nick Durante is a professional writer with a primary focus on home improvement. When he is not writing about home improvement or taking on projects around the house, he likes to read and create art. He is always looking towards the newest trends in home improvement.

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