Suspended sediments (SS) constitute the major part of river loads. Their grain sizes predominantly are smaller than fine sand. The deposition of SS in the floodwater harvesting systems (FWHS) affects several characteristics such as infiltration rate, aquifers recharging, soil fertility, plant growth and soil water capacity. Although numerous advantages and a few disadvantages were listed for the sediment deposition in FWHS, due to lack of measurements on particle size distribution of SS, inclusive assessment on sedimentations has been impossible up to now. To overcome this limitation, the texture and particle size distribution of more than 100 fine deposit samples taken from 18 sedimentation areas across the country were analyzed. The results showed the dominance of silt (average 46%) followed by very fine sand (average 20%) that totally composes 66-93% (average 83%) of deposited fine sediments. This indicates that coarser (> 2m) particles comprise the major partition of the SS. On the other hand, the texture of most samples is loam and silt loam, which represents a medium to coarse texture. Therefore, the infiltration rate of the FWHS reduces to an optimum level without becoming a limiting factor. It seems that some other factors including high deposition thickness at an event, a layered structure with alternating clay layers and failure in plowing and cultivation are responsible for reducing the permeability of FWHS.