Which sediment size would allow water to flow through at the fastest rate?

The sediment size that would allow water to flow through at the fastest rate are pebbles. Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is consequently transported by the action of wind, or ice, and or by the force of gravity acting on the particles. Pebble is a clast of rock with a particle size of 2 to 64 millimeters based on the scale of sedimentology.