This study assessed the performance and developed a simple approach for estimating infiltration capacity of two infiltration gutters by using on-site tests. Permeable-brick and redbrick infiltration gutters were constructed on-site. Water infiltrated from the surfaces of two vertical sides (NFS-2S), bottom (NFS-B), and three faces (NFS-3S) of two gutters were measured under nonflowing and steady-state conditions. Tests results from NFS-2S and NFS-3S indicate that the permeability and water depth for both gutters are linearly dependent on each other. Experimental results also indicate that, when the bottom of the gutter is clogged, the permeable-brick gutter still retains approximately 93 and 79% for redbrick gutter of their infiltration capacity for NFS-3S. On the whole, permeable-brick gutter has an advantage over redbrick gutter in stormwater infiltration. Based on these results, the permeability for different water depths and widths of these two gutters can be obtained.