Collecting water from the air has been a practice for some 2,000 years, in the form of “air wells” in Middle Eastern deserts, and later in Europe. Around the 1400s, we see water-collecting Dew Ponds, and later the Fog Fences, which have for hundreds of years have been used in Europe to collect clean water from the air. In the early 1970s, Melvin Littrell began producing water from the air with a system that did not need a compressor. Through this development, the creation of the first real Atmospheric Water Generator was produced. In 1990, Littrell patented the system’s technology as an AWG or atmospheric water generator.
They are available in various sizes and styles, ranging from domestic systems that produce 32 oz. a day to all-electronic units producing 75 liters per day with compressors, and finally to commercial applications that can produce from 35,000 to 109,000 gallons of water each day.
 Principle of operation
The principle of operation remains similar for most manufacturers except the WPG. The AWG is essentially a conventional dehumidifier that condenses water from air. A compressor circulates refrigerant through a coil or chiller array. A controlled-speed fan pushes air over the water reaction area and condenses the water. This water is then passed into a holding tank.
The rate at which water can be produced depends on relative humidity and ambient air temperature and altitude. Relative humidity is the amount of water vapor present in the air at a given temperature at a given time. AWGs become more effective as relative humidity and air temperature increase. As a rule of thumb, AWGs do not work efficiently when the temperature falls below (35°F), the relative humidity drops below 40%, or at high altitudes (above 4000 feet). If the ambient air has passed through an air conditioner, much of the water vapor has already been removed. In the winter, with a heater on, most of the humidity is lost, leaving little for the AWG to produce.
 Optional AWG features
AWG features vary depending on the manufacturer. In order to meet stringent FDA standards and NSF, most systems are coupled to one or more advanced filter systems (including an UV light chamber) before being stored in stainless-steel holding tanks. A list of optional features typically found in AWG systems would include:
- An air filter to help prevent dirt from accumulating on the surface of the coil
- An automatic level switch placed in the generator’s holding tank to shut the machine off when the tank is full
- Hot and cold stainless-steel storage tanks that allow water to be served heated or chilled
- The so-called “split system” is a two-part system. Designed by Prof. James D. Vagarasoto in 1991, the two-part system allows the user to place the generator in a location of high humidity and serve as a tabletop unit that dispenses hot or cold water. These systems eliminate the adverse effects of most older-style atmospheric water generators, as they heat the area where the generator is placed. In the summer, air conditioning system remove most of the humidity, so the conventional AWGs don’t work very well because they are humidity-driven.