Percolation Calculator

Percolation testing, commonly referred to as a “perc test,” is a method used to evaluate the absorption rate of soil for septic systems and drainage projects. During this test, holes are dug in the soil, filled with water, and the time taken for the water to seep away is measured. This process is critical in determining whether the soil is suitable for a septic system or for assessing its general drainage capacity. The results of a perc test are essential for making informed decisions in construction, landscaping, and environmental planning, as they directly impact the design and feasibility of septic systems and other drainage-related structures.


This tool is designed to assist with percolation testing, providing a streamlined and accurate way to calculate soil absorption and drainage capabilities. It’s particularly beneficial for contractors, landscapers, or anyone involved in soil percolation tests. By inputting the number of test holes, the depth of water in each hole, and the time taken for the water to drain, the calculator processes these parameters to deliver precise percolation rates. It offers the flexibility of using either imperial or metric units and converts the input data into standardized units of measure, either minutes per inch (mpi) for imperial or seconds per milimeter (sec/mm) for metric. This calculator simplifies the complex process of percolation testing, making it more accessible and efficient for professionals across various industries.

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Step 1: Choose the unit system: Select either the “Imperial” or “Metric” option depending on your preference for measurements. This will determine whether you input and receive results in minutes per inch or centimeters per second.
Step 2: Enter the number of percolation test holes: Input the total number of holes you’ve dug for the percolation test. This will allow the calculator to process data for each individual hole.

Step 3: Input depth drained for each hole: For every hole, measure the depth of the water before and after the draining time, then input the difference in depths (in inches or centimeters, based on your selected unit system).

Step 4: Record drainage time: Log the time you allowed the water to drain. Ensure accuracy as this data is crucial for calculating the percolation rate.

Step 5: Check your average percolation rate (In Vp for metric or mpi for Imperial).


Percolation Calculator Disclaimer

Users are advised to exercise caution and use their professional judgment when relying on the results generated by this tool. The Percolation Calculator does not replace the need for thorough on-site assessments and professional expertise in soil evaluation for septic systems and drainage projects. The calculator’s results should be considered as preliminary information and not as a definitive determination of soil suitability.


The creators and providers of this Percolation Calculator are not liable for any inaccuracies, errors, or omissions in the results, nor for any decisions or actions taken based on the information provided by the calculator. Users are encouraged to consult with qualified professionals, such as soil engineers or environmental specialists, for comprehensive evaluations and decisions related to soil percolation testing.


By using this Percolation Calculator, you acknowledge and agree to the terms of this disclaimer. If you do not agree with these terms, it is advised not to use the calculator for making critical decisions.

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