A percolation test determines the soil's ability to absorb fluids for the installation of a septic system. A septic system uses a tank to collect a home's wastewater and solids where it breaks down through an enzymatic process. The fluid releases from the tank through pipe that leads to a series of perforated pipes buried a few inches below the surface of the ground called a leach field. While you can certainly check the soil's ability to absorb fluids yourself, to get a septic permit in in some states, including California, you need to have a registered geologist, civil engineer or environmental health specialist complete and certify the test.
Choose the area where you plan to install the septic system. For instance, the tank itself typically installs within a few feet of the home, but piping from the septic system leads to the leach field installed several feet away from the home. Insert a wood stake into the ground by using a mallet to identify the location of the planned leach field. Pick an area where the ground slopes less than 30 percent to comply with percolation test and septic system installation requirements.
Fill the hole with water. Measure the time it takes for the hole to drain using your watch The amount of time it takes for the hole to drain the water determines whether you can install a regular septic system or a specially designed one. Test holes that drain at a rate below five minutes per inch, greater than 30 minutes per inch in a deep trench or longer than 60 minutes per inch, require a special septic system designed for the soil's percolation.