Percolation occurs when the water on the earth's surface in the run-off stage seeps underground. After run-off comes the last step of the water cycle: percolation! That is why in the old days they used wells to retrieve water! When groundwater is depleted, recycled water can be introduced into aquifers by letting it gradually filter through the soil When you hear the … Water that is in the zone of aeration where air exists is called vadose water. The water cycle indicates the movement of water in and out of the atmosphere through different phases of matter. Percolation is a natural process in which surface water is gradually filtered through the soil into aquifers. It was under the Earth's surface! Percolation is part of the water cycle that occurs after precipitation and before storage during which water filters down through aerated soil due to gravity. Much like a coffeemaker percolates water from top to bottom, water percolates down through soil until it … Percolation is the movement of water though the soil, and it's layers, by gravity and capillary forces. The prime moving force of groundwater is gravity. After percolation, water is stored in groundwater reservoirs until it reaches a point where sunlight warms it and the water evaporates. A well is an … Water that is in the zone of saturation is called groundwater.