This paper presents experimental results obtained from tests on unsaturated soil in one-dimensional columns simulating a rainfall infiltration process. Six columns composed of compacted Silty Sand were prepared to study the effects of the initial water content and rainfall intensity on the downward infiltration process. The advance of the water front was monitored using sensors to measure pore water pressure and volumetric water content installed at different locations along the height of the Silty Sand column. The test results show that the lag time, defined as the time difference from the beginning of the test to a sudden increase in the volumetric water content readings, was influenced by the soil initial water content and rainfall intensity; it is observed that the lag time is shorter at higher initial water contents and greater rainfall intensities. The results provide insights to understand the hydraulic behavior of unsaturated slopes and embankments exposed to rainfall infiltration.