Abstract: A vadose zone for a leaching field which enables the construction of a leaching field in terrain where conventional leaching fields cannot be constructed. Such terrain also comprise areas where a high water table exists or where percolation tests fail. The vadose zone is constructed adjacent to the leaching field which is buried in a layer of soil which has been constructed over a nonporous barrier such as a plastic sheet or ledge or clay. The effluent from the leaching field is forced to move sideways out of the leaching field into the adjacent soil. The adjacent soil becomes a vadose zone to complete treating the effluent. The effluent is forced to flow through a prescribed predetermined distance through the vadose zone before it is permitted to disperse through the soil toward the water table or over the clay or ledge.