FAQs for Perc Testing and Septic Systems

Perc Testing

A “Perc Test” or “Soil and Site Evaluation” is the process of evaluating the physical soil properties, landscape, and site features of a parcel of land to determine its suitability to site a septic system.


If your site fails a Soil & Site Evaluation with the Local Health Department, and your Improvement Permit application was denied, you can either appeal their decision or they will recommend you hire a Soil Scientist to evaluate the land for Alternative and Innovative system types.

An Improvement Permit/Construction Authorization issued by a Local Health Department is valid for 5 years. An evaluation by a Licensed Soil Scientist does not expire; the results will generally stay the same so long as the area evaluated does not physically change.

The cost of a perc test varies based upon the total acreage being evaluated, the number of perc sites desired, site vegetation and landscape, site location, and the overall goals the client has for the site. A perc test for a 1-acre site will start at $600 and increases depending on the aforementioned variables.

Potential options could include hooking up to municipal sewer systems, assessing adjoining properties for easements, or pursuing a state direct discharge system.

A soil scientist is someone who is licensed in the practice of soil evaluation. Licensed Soil Scientists have to pass professional exams and meet experience and continuing education requirements.

Septic Systems

Septic systems vary by magnitudes in pricing based upon the specific system type. The system type is determined by usable soil depth, available space, and amount and type of wastewater. Prices range from a several thousand dollars for a conventional gravity system to $40,000+ for an aerobic drip system.

The most basic septic system is a conventional system with gravel or gravel-less trenches and utilizes gravity to distribute the wastewater. From there, they increase in complexity to pump-to-conventional, pump to pressure manifold and low-pressure pipe, with the most complex systems being subsurface drip.

All septic systems have their pros and cons, require regular maintenance, and can fail if not taken care of. However, conventional systems, if installed properly in the appropriate soil conditions, require the least amount of maintenance and upkeep. These systems can last for decades with proper maintenance.

The type of septic system required varies by site and is determined based upon usable soil depth, available space for the drain field, topography, type and amount of wastewater, and other site features that may impact the wastewater system.

A conventional septic system is the most basic on-site subsurface wastewater system. It involves a septic tank, a distribution box, and a drain field consisting of either gravel drain lines or manufactured gravel-less drain lines. Conventional systems require the deepest usable soils (>30″) in order to be installed.

An engineered septic system is required when the soil and site conditions are severely limited. These engineered systems are designed to overcome the complex site constraints with multiple pumps, pre-treatment hydraulic units, and a variety of innovative features. Three Oaks does not currently provide septic system engineering; however, we can put you in contact with a reputable engineer.

Septic drain fields that are sited upslope of the septic tank require a pump to deliver the wastewater to the drain field. Pressure-distribution systems also require a pump. These systems include low-pressure pipe, drip dispersal, and systems utilizing a pressure manifold to deliver wastewater to a complex drain field layout.

Request a copy of your septic permit from the local health department and it will show where the tank is approximately located. Probe rods and ground-penetrating radar (GPR) can be used to search underground for the tank lid.

Load More