Sand absorbs water because sand particles have pores in them that, when dry, are filled with air. When the sand particles are wet, the air in the spores is replaced with water.
Sand is filled with pores that enable it to absorb water. The absorbency of the sand, or the water holding capacity, depends on the texture of the grains. Dune sand generally has finer grains than beach sand because it is the lighter, finer sand that is picked up and moved by the wind and water.
According to Plant & Soils Sciences eLibrary, fine soils and medium-textured soils can absorb the most water, which includes sandy loam. Coarse soils such as sand have less of an ability to hold water because of the limited amount and smaller size of the pores.
Sand by itself, without containing loam, silt or clay, has the least absorbent water capacity of all the soil types. Coarse sand has a water holding capacity of 0.25 to 0.75 inch of water per foot of soil and fine sand has a water holding capacity of 0.75 to one inch of water per foot of soil, as opposed to the more than two inches of water found in one foot of silt loam.