Originally Published: January 24, 2014 7:51 a.m.
Q: We are interested in doing our part to conserve water and would like a simple explanation of rainwater harvesting components.-Tom and Lilly, Prescott.
A: Did you know that one inch of rain on a 1,000-square-foot roof can yield roughly 600 gallons of water. Rainwater harvesting is the practice of capturing, diverting and storing rainwater for plant irrigation and other uses. There are two types of rainwater-harvesting systems; active and passive.
The components of an active system are rain barrels, usually 50 to 100 gallon and/or cisterns of 100-gallon capacity plus. There are many potential uses for captured active rainwater, such as watering plants and washing cars. By "actively harvesting" rainwater, this means that you are collecting, storing and recycling water that would otherwise be sent to municipal sewer systems. While these systems are more complex and more expensive than passive systems, they have the advantage of reducing the costs for municipal water and water treatment. Rainwater systems can be more easily added if they are planned for irrigation or specialty uses, and there is adequate space available for the processing and storage systems. Arizona Seamless Gutters on 6th Street in Prescott is a wonderful resource for rain barrels and system collection and information.
It is relatively easy to get started with an active harvesting system, because you just need to purchase or make rain barrels out of a food-grade drum and a hose spigot. The rain barrel needs to be positioned under a roof downspout and when it rains - collection is underway! With an active system, you need to plan for overflow or make sure your direct the excess water to other outdoor vegetation areas. It is important to keep the rain barrels covered with screens to prevent mosquito breeding and other debris from entering the collection site.
Passive rainwater collection systems are made from berms, basins, rain gardens and swales that have been created in a yard. Passive systems rely on micro-topography to direct water toward depressions in the landscape where water will infiltrate the soil and benefit the landscape plants. Depending on the size of your yard and area for collection, you could achieve a far greater storage area because soil has more capacity than a tank. Water runoff from the roof and/or driveways would have to be directed to the ponding and retention area. In most cases this would and should involve the work of a landscaper to ensure that the water is being captured correctly and that your plants can handle water inundation and also periods of dryness. These areas should also be landscaped so it looks like a nature part of the yard. If you are considering installing a passive rainwater-collection system, it would be wise to obtain a soil test to determine whether the site is suitable for water collection.
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