Abstract: A heat and water integration process for an oil sands operation includes subjecting warm oil sands tailings to thickening to produce thickened tailings and warm water overflow; subjecting the warm water overflow to direct steam injection (DSI) to produce steam heated thickener water; providing the steam heated thickener water to a unit of the oil sand operation; and producing the warm oil sands tailings from the oil sands operation. The oil sand operation unit may be an oil sand ore preparation unit and/or a primary separation unit, for example. The heated thickener water can replace water taken from pond inventories. The DSI may use excess, low quality, wet, low pressure and/or blow-down steam. The process enables improved heat and water usage in oil sands processing.