As shown in the illustration above a surface inlet to an infiltration trench may simply be a channel of decorative [[stone]] supported by a [[geotextile]]. So that at grade it may be indistinguishable from a [[gravel diaphragm]]. In function though, the decorative surface course of the infiltration trench needs to remain free-draining down into the trench, whereas the gravel diaphragm is designed to spill over onto adjacent land, leaving sediment behind in the [[gravel]] or [[stone]] channel.