Drainage water is reused to extend water resource, as drainage water becomes recharge in irrigation delivery systems, recharges groundwater that is pumped for irrigation, and more recently, to maximize salt storage within the root zone and minimize the drainage volume.  As water is cycled through the root zone, evapoconcentration increases the concentrations of salt and potentially toxic trace compounds.  Accumulation of sodium and magnesium coupled with precipitation of calcium as gypsum or calcium may result in deterioration of soil physical problems.  Potentially toxic trace elements such as selenium may also be concentrated to levels of concern.  As background to the discussion, existing and proposed systems for cycling drainage water to minimize the end volume and water and soil quality problems resulting from use of poor quality drainage waters are reviewed.  Numerical models show that there is a minimum in the relationship between the amount of irrigation water applied and the amount of drainage and that the soil and plant have a significant influence on the water and salt budgets.  The self-regulating nature of the system is explored through numerical simulations.  New low flow-high frequency dripper systems provide additional control of the system that surface irrigation systems cannot provide.  Two dimensional simulations of water and salt movement around a high efficiency dripper are used to explore the potential for increasing salt storage and disposing of drainage water.