To remove soluble or other constituents from a medium by the action of a percolating liquid, as in leaching salts from the soil by the application of water
The roots of the word are Old English leccan, to water The definition is to dissolve out For example, heavy rains have leached the minerals from the soil
the process of leaching remove substances from by a percolating liquid; "leach the soil" permeate or penetrate gradually; "the fertilizer leached into the ground" cause (a liquid) to leach or percolate
To dissolve out by the action of a percolating liquid in order to separate the soluble components (Merriam Webster's Collegiate Dictionary, Tenth Edition)
Water that collects contaminants as it trickles through wastes, pesticides, or fertilizers Leaching may occur in farming areas, feedlots, and landfills, and may result in hazardous substances entering surface water, ground water, or soil