Rain Water Harvesting
A rainwater harvesting system collects water from a roof and diverts it to a storage tank where it is then used either inside or outside a building or home. Designs range from a simple rain barrel at the bottom of a downspout for watering a garden to extensive cistern systems that can provide a substantial amount of the water for cooling tower make-up, irrigation systems, water features, and vehicle washing.
Air Conditioning Condensation Harvesting
Cooling systems rely on evaporator coils through which refrigerant fluid changes from liquid to vapor, cooling the coils in the process. Air blowing past the coils cools off as it goes by, and moisture from the air condenses on the coils. Condensate drains carry away the water, usually into the sewer. Instead of wasting it, more and more buildings, especially in parts of the country with hot, humid summers, are capturing that condensate for reuse.
Grey Water Re-Use
As the term is most commonly used, gray water refers to wastewater from clothes washers, showers, bathtubs, and lavatory faucets—and not water from toilets, kitchen sinks, and dishwashers Gray water is collected with separate drain lines (requiring a building to be dual-plumbed for gray water and other wastewater drainage), filtered to remove large particles, and stored until use for landscape irrigation—usually below ground.