Filtering and storage of water 

Depending on soil properties, precipitation water is partitioned into storage, groundwater 
recharge, evapotranspiration, and surface runoff. Due to its porous structure, water can infiltrate into soil and is  retained there via capillary forces just like in a sponge, so that it is available for plant growth and the development of other organisms. This reduces droughts and the generation of floods. Solutes and particles moving through soil have to pass the extensive inner surfaces of soil 
constituents where they might be sorbed or transformed. Hence, soils are also important to 
filter harmful substances, originating from industrial and agricultural production, municipal 
activities, or atmospheric deposits.