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(PDF, 2MB) 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.
Water Harvesting Guidance Manual(PDF, 2MB)
Water Harvesting - Commercial and Residential
A. Commercial Properties
Non required PDSD water harvesting may be incorporated within the ROW under the following conditions:
- Water depth is less than 8”
- Water does not cross over the public sidewalk
- Water does not stand longer than 24 hours
- Plans are submitted and approved by TDOT Stormwater
- Two types of passive water harvesting may be developed by residents within the public ROW:
- Swales (areas excavated to a depth of not more than 8” to collect water that runs off the adjacent property)
- Curb Opening and water harvesting basins (Curb cuts or core drills that allow street run off to enter the ROW between back of curb and the pedestrian sidewalk into basins). See standard basins details below.
- Projects must first be designed and submitted for review by TDOT Landscape Architect. (see sample submittal package)
- Curb cuts or core drills and water harvesting basins must obtain a TDOT permit. (Type a. basins see item 1 above, should be reviewed by the City but will not require a permit).
- Curb cuts and core drill work must be done by a registered contractor.
Residential Water Harvesting Details
Landscape Architects Water Harvesting Details