Soil & Site Evaluation
The ability of soil to accept water or for water to travel through soil is called soil permeability.
Percolation is the movement of water through soil. A soil percolation test is designed to measure the rate of water movement in saturated soil (mimicking conditions that soil treatment systems have) so that one can decide the appropriate type and size of treatment system.
The test measures how quickly an inch of water will drop in a hole after the soil has been saturated with water, and results are given in minutes per inch. Soil that is best suited for a soil absorption system will allow water to move at a slow enough rate for treatment to occur (slower than 5 minutes per inch), yet fast enough to accept more wastewater as it is generated (faster than 60 minutes per inch).
Use this Natural Resource Conservation Service link to access Soil Survey Maps and reports online.