Air conditioning and refrigeration are used around the world to keep rooms cool and preserve food. As the air is cooled it is dehumidified, removing water as condensate. With proper treatment to take care of biological contaminants, this water can be constructively used.
Condensate is essentially distilled water, although it may contain bacteria that can create illness. The biggest concern is Legionella: airborne bacteria that are amplified in air conditioning condensate. While natural sources of water are not contaminated, Legionella can become a problem when an amplifying device like an air conditioner is present. Ultraviolet light, chlorine tablets or raising the water temperature can reduce the hazards.
So, how is reclaimed air conditioning condensate used? This high quality water with low mineral and chemical content has many potential uses. This water is great for landscape irrigation. With biocide treatment it can be used in swimming pools and as domestic potable water in areas where water is limited. It is also a good source of water for cooling towers or industrial processes.
Hybrid air conditioning systems are being developed that route the condensate into a rainwater cistern. This water should be considered gray water, but is useful for lawn irrigation. This often overlooked source of freshwater can be constructively used in areas where potable water is at a premium. As water shortages become more widespread, condensate from air conditioning is gaining increased attention.