Pore-throat characteristics of porous media play important roles in various flow processes. However, pore size distribution (PSD) and throat size distribution (TSD) of various porous media have rarely been reported. Watershed-segmentation (WS) is a promising pore-throat identification method. To avoid over- and under-segmentations, a trial-and-error method was devised and validated using artificially ordered packings. Afterwards, we analyzed porous media with various characteristics, and comparisons with artificially ordered packing were made. More angular particles generated larger pores and throats. TSD of spherical particles was bimodal, whereas other particles resembled a normal distribution. Pore surface area and volume relation demonstrated a fractal behavior. Compared with medial axis (MA) method, PSD and TSD from WS method were larger but exhibited similar distribution trends. Normalizing the PSD with the median pore size yielded a single Gaussian model, demonstrating a possible PSD model. However, normalization to TSD data does not produce a single Gaussian model. Display omitted •Watershed method to identify pore−throat of various unconsolidated porous media•Spherical particles generate smaller throat but larger pore than angular particles.•Comparison to medial axis method shows similar trend but larger pore and throat.•Relationship of pore volume and surface area demonstrated a fractal behavior.•Normalized pore size distribution demonstrated a single Gaussian function.