Water Harvesting is the practice of capturing and collecting runoff from storms and using the "harvested" stormwater to provide supplemental water for landscape plants. Water harvesting has numerous benefits. Water harvesting reduces the amount of stormwater flowing in streets or onto adjacent properties, increases the quantity and quality of the water supply for landscape plants, and helps keep potential stormwater pollutants out of our streets, watercourses and ultimately, the groundwater. Water harvesting appropriately designed and monitored, can reduce the amount of potable water used for irrigation, saving a development money and reducing the demand on the City's potable water delivery system.
One simple and cost effective way to help reduce potable water consumption is to reduce irrigation water use for landscaped areas. An average water use breakdown for properties in Tucson indicates approximately 60% internal use and 40% is external use. Presently, the only water use reduction program or method enforced by the City that targets landscaping water use is the Xeriscape requirements in the Land Use Code. The Land Use Code provides additional means to reduce external water use by requiring stormwater harvesting to supplement irrigation systems for commercial developments.
Technical experts acknowledge that widespread, individual efforts to harvest stormwater could affect rates of stormwater runoff. While not practical as a regulatory approach for managing stormwater on a City-wide basis, water harvesting should be encouraged for use by individuals on private property. If enough people practice water harvesting in City neighborhoods, it is possible that some urban flooding problems could be reduced.
The Water Harvesting Guidance Manual was developed in accordance with Mayor and Council direction. On October 18, 2005, the Mayor and Council (M&C) passed an Ordinance supporting the Water Harvesting Guidance Manual for use by developers in planning a strategy to implement water harvesting for new developments, including City projects.
The manual is primarily directed toward commercial developments, but the concept designs and configurations are easily adapted for residential lot use. Adobe Acrobat Reader (downloadable free online) is needed to view the document. If you have any questions, please call the City of Tucson Stormwater Management Section at (520) 791-4251.