The present invention includes a method and apparatus for determining the percolation rate of soil. The method includes providing a test assembly configured to be placed over the top of a test hole, the test assembly containing a remote sensor (such as an ultrasound sensor) positioned proximate the top of the hole. The depth to the bottom of the hole, as well as the elevation of water within the hole during the test process, is measured using the remote sensor and used to determine perc rate of the soil within which the hole is dug.