Permeable pavement systems with deep aggregate layers were studied to see how well they clean stormwater. The pavements were tested in an urban area, and samples were taken from both regular runoff and water captured by the pavements. The results showed that these systems reduced levels of dirt, bacteria, and nutrients in the water. On average, the systems decreased dirt levels by 47% and bacteria levels by 69%. The amount of pollution removed varied depending on how hard it rained. This suggests that the benefits of these pavement systems for water quality depend on the intensity of rainfall.