An innovative diffusion driven desalination (DDD) process is presented, and its performance based on thermodynamic considerations is thoroughly explored. The desalination is driven by water vapor saturating low humidity air flowing through a diffusion tower Liquid water is condensed out of the air/vapor mixture in a direct contact condenser The desalination process is suitable for operation at low temperatures and may be driven by waste heat with low exergy. It is demonstrated that the DDD process can yield a fresh water production efficiency of 4.5% with thermal energy consumption of 0.56 kWh per kilogram of fresh water production based on a feed water temperature of only 50degreesC. An example is discussed in which the DDD process utilizes waste heat from a 100 MW steam power plant to produce 1.51 million gallons of fresh water per day.