Rainwater collection is a water management strategy for designing buildings and habitats to use water from rain for a variety of things.
Types of Rainwater Collection
There are two main types of rainwater collection.
Water collected directly off of buildings and designed to be used as potable water.
Systems used to manage water on landscapes and store excess water for irrigation or other nonpotable use
Potable water systems are best suited to environments where water is in medium abundance such as the Hill Country of Texas where they normally get about 30 inches a year. There are various types of strategies for collecting rainwater including the use of dams and empoundments to manage ground water runoff on properties which are great in arid or semi-arid environments where water is a precious commodity for landscaping.
Building dams is an especially useful Dryland Permaculture strategy in arid and semi arid environments for reducing erosion while increasing sub surface aquifer reserves on the property. In addition, the adding of dams on a property can increase flora which adds to the ecological capacity of the site and also reduce the tendency for soil to be removed by heavy rains. It also can help to recharge aquifers by adding the capacity of the land to hold water rather than allow it to flow rapidly off the property through riverbeds.
The major association with rainwater collection though is the act of designing rooftops and landscapes in habitats as water collection zones so that the water is collected through a series of channels, baffles and tanks. Channels direct the water flow from roofs and patios, sidewalks, etc to filtration and storage areas. Baffles are then used in conjunction with biofilters made up of sand in small tanks called traps. Then the water is stored in water storage tanks called cisterns.
Introduction to Invisible Structures RainStor Grid Erosion Control Sytems in 2000 During Ecosa
During the Ecosa Institute Total Immersion on Ecological Design Course seminar at Arcosanti in 2000 that I participated in, a representative from a company called Invisible Structures talked about their company and its products which related to Ecological Design and specifically landscape erosion control and water management. They had developed five products for a variety of uses such as alternative pavements that absorb and store water, grid type layers that go under grass to add water storage capacity and reduce erosion esp on hills, fabrics and materials for green roofs and ground storage systems that use a molded plastic square that can be stacked and made into an underground cistern.
David Tollas Leads RainStor Cistern Project at Arcosanti in 2011
In 2011 Arcosanti began reconsidering its rainwater collection plan. This include a consideration of what to do with the 44 Rainstore3 tiles/panels were received from a distributor of Invisible Structure products located in Pheonix. After considering the best location, we began installation of these panels in an area at the end and below the Heat Duct Tunnel located and also just below the pool slab.
Arcosanti Water Management Strategy
At Arcosanti we have designed the area around the East Crescent to be used as a the focus point for the rainwater collection system. With rainfall within that area at around 13-16 inches a year we estimate that the water collection that will be available will be in the range of 100000 gallons per year. Currently we have two cisterns with an approximate capacity of 1000 gallons each. These cisterns are in the basement of Units 6&7 Lightscoops in Phase 5 of the East Crescent.Â
The addition of this rainwater collection system will boost the capacity of the existing rainwater storage by abount 30 percent as the 44 Rainstore3 panels have an estimated capacity of 25 gallons per panel (25x44=968) with a total capacity of 1000 gallons.
Arcosanti Water Cisterns
The current system is unused but when the additional capacity is online we do plan to develop a system for using this water in the irrigation of the landscape around the Energy Apron Greenhouse being constructed around the Guestrooms. We also have tentative plans to collect the water from the Guestroom/Energy Apron Greenhouse rooflines and store that in underground tanks for landscaping and/or possible greenhouse irrigation uses.