Due to these large pores and high drainage rate, contaminated water passes unfiltered. When this unfiltered water passes through the gravel, it introduces contamination into the aquifer and can cause pollution of the entire aquifer. Lab 3-A: Soil Permeability Permeability is the process by which a liquid or gas passes through another substance. In this laboratory case, it is the time and rate at which water passes through various soil samples. Several soil samples were used, including gravel, sand, loam, and soil from my backyard. All four had variable permeability and drainage rates when subjected to the laboratory experiment. The sample that presented the highest permeability was gravel. Due to the size and abundance of pores in the gravel sample, water passed through it almost unimpeded. The pores of the rocks that made up the gravel sample retained 16%, or 8 ml, of the 50 ml of water used. Furthermore, these large pores allowed for a drainage rate of 0.186, which was the fastest among all samples in this experiment. If the pores were smaller, water would permeate more slowly and have greater water retention