Aeroponics systems, by their nature, uses water more efficiently than hydroponics - as much as 30% less. In aeroponics systems, nutrient solution is applied as a very fine mist in carefully calculated intervals. Supplied by plentiful oxygen, the roots are able to immediately absorb the nutrients and water provided and put them to use immediately, so there is virtually no waste. The precise nature of aeroponics systems means they require less nutrient solution overall.
Hydroponics systems, on the other hand, are based on keeping roots immersed or at least partially covered in water all the time. Larger amounts of nutrient solution must be maintained, and much of it isn't used before it needs to be replaced. Loss of water through evaporation is also reduced in aeroponics, where both the nutrient reservoir and the root chambers are sealed. In hydroponics, the reservoir and nutrient channels are typically open.
