Available water is an important term in the world of plants and gardening. Having a pond 10 feet from a garden would seem to define the term 'available water', but it does not. Wilting plant leaves can be caused by too little or too much available water. A plants roots need to be able to extract water from the soil. The plant cannot do that if the soil is over saturated or the soil is too dense and water logged for water extraction. The ideal soil contains about a 50-50 mix of water and air. The 50-50 mix allows for good water movement as the plant roots attract moisture from the soil. The right mix of water and air will provide the most 'available water' for your plants.

Clay soils can hold the most water but many times they hold the moisture very tightly and thus it is not as available as other soils. Sandy soils are much more coarse and moisture tends to drain away quickly because of gravity, so the same amount of rain may cause a plant in sandy soil to moisture stress much faster because the moisture becomes unavailable to the root area. Medium textured soils offer the most water availability. Moisture is more 'available' for a longer period of time because the plant roots have more 'space' to access the moisture..