Limited information exists on bacterial community richness anddiversity in surface water CW system. In a large-scale horizontal subsurface flow CW (HSF-CW) system used for the purification of polluted river water, the inlet zone was found to have higher sediment bacterial richness and diversity than the outlet zone. also indicated that the influent of a full-scale surface water HSF-CW had higher bacterial richness and diversity than the effluent. In contrast, the diversity of bacterial community attached on ceramic particles was found to increase with increasing wetland layer depth in a pilot-scale surface water VF-CW. So far, the substrate effect on CW bacterial richness and diversity remains unclear. reported a different s depth-related change pattern of bacterial diversity in three pilot-scale surface water VF-CW systems. In gravel VF-CW, a continuous increase of bacterial diversity was found with increasing wetland layer depth. Bacterial diversity illustrated a considerable increase followed by a slight decrease in sand VF-CW, but a considerable decrease followed by a remarkable increase in zeolite VF-CW. However, in the present study, the three lab-scale VF-CW systems showed similar depth-related change pattern of bacterial diversity. Bacterial diversity showed a decrease followed by an increase. Moreover, the present study suggested a slight substrate effect on bacterial diversity in VF-CW system, in agreement with the result found in VF-CW system treating piggery wastewater. In addition, the three studied lab-scale VF-CW systems showed much different depth-related change pattern of bacterial richness. A considerable substrate influence on bacterial richness was observed. These results were different from those found in bacterial diversity.