Rainwater harvesting, a practice supported through of Pima Association of Governments’ Stormwater Program, captures or slows down surface stormwater so that it can be put to beneficial use. When we harvest rainwater, we can use it to irrigate surrounding vegetation to help beautify the landscape and increase shade without depending on groundwater.
How to Harvest
Rainwater harvesting practices can be active or passive. Active rainwater harvesting uses gutters and downspouts to direct water into cisterns that store water for future use. Passive rainwater harvesting uses depressions and/or berms called "earthworks" to store water in the soil, where it can be used by vegetation. Plant the Water Handout (pdf)
Water conservation in a Sonoran desert community is an important community practice and can results in many benefits.
- Broad-based implementation of rainwater harvesting could reduce municipal water demand by reducing the need for potable water for irrigation, which accounts for over a third of household water use in Tucson.
- Rainwater harvesting also prevents water from running into the streets, where it can pick up pollutants that are then transported into washes.
- Broad-scale rainwater harvesting could result in decreased floodwaters and reduced erosion near culverts and other flood control devices in drainage areas.
- Incorporating rainwater techniques into residential landscapes has the potential to increase property values by meeting LEED green building requirements.
- Rainwater harvesting is key to building urban green infrastructure. Storing water in the soil for vegetation provides a cascade of effects such as providing habitat, reducing the urban heat island effect, cooling and shading urban neighborhoods and improving air quality. Such stormwater management that mimics natural processes and maintains natural functions is known as Low Impact Development (LID).
Tracking our Progress
Click here to view a timeline that shows rainwater activities in the Tucson area since 1989, when Trees for Tucson planted its first 60 trees using rainwater harvesting principles.
Presentations and Meeting Info
- See links below to Videos and Speaker Series details as presented at PAG's Sustainability and Energy Expo, which was held March 6-7, 2009. A Desert Rainwater Harvest Forum included discussions led by local experts.
- PAG's Rainwater Harvesting Resolutionwas adopted by the Regional Council on Oct. 9, 2008. The resolution identifies rainwater harvesting as a practice that is beneficial to the proper management of water in a desert environment and encourages member jurisdictions to take action to increase the use of water harvesting.
- Watershed Planning Subcommittee Minutes including presentation from James MacAdam, Watershed Management Group, regarding a grassroots model for empowering demographics in water sustainability efforts through accessible RWH techniques.
- Environmental Planning Advisory Committee minutes, including a presentation from Brad Lancaster, local author of Rainwater Harvesting for Drylands, discussing RWH incorporation into water resource management. Ann Audrey, City of Tucson's Office of Conservation and Sustainable Development, provided information on the city's current RWH policies.
RWH Events in the Community:
External Links to More Resources:
Regulations (See incentives below)
Rainwater harvesting often takes place in the urban environment. As a result, local municipalities have developed guidelines and ordinances to help citizens understand how to harvest rainwater. If you are planning to install a system, please read through the following to learn about regulations that might influence your plans or incentive programs that might help you pay for your system.
Use caution in using gabions that divert stream flows because development in a wash may require a Floodplain Use Permit from the City, and/or a Clean Water Act Section 404 permit from the US Army Corps of Engineers.
In the Landscape
On Oct. 14, 2008, the City of Tucson Mayor and Council adopted a Rainwater Harvesting Ordinance, the first of its kind in the United States for commercial developments. Tucson requires commercial properties to use rainwater for 50 percent of site vegetation water budget for permits issued after June 1, 2010. With this, Tucson became the first city in the country to require rainwater harvesting for landscaping use. In addition to cisterns, the regulations allow berms and contoured slopes to be used to direct rainwater to trees and landscaped areas.
According to building codes, developers will have to submit a landscape water budget in a plan. The Development Standards are still being developed but this agenda package for the Tucson Mayor and Council meeting, where the ordinance was adopted, explains the anticipated requirements.
Since February 1991, the Xeriscape Landscaping and Screening Regulations - Ordinance 7522 has required the use of drought-tolerant plants from a published list and limits non-drought tolerant vegetation to small "oasis" areas where turf may be used. This applies to new multifamily, commercial, and industrial development. Oasis areas for facilities are restricted to 2.5 percent of a site for commercial development and 5 percent for multifamily.
The City of Tucson encourages rainwater by allowing incorporation of rainwater harvesting elements in development designs to meet stormwater regulations requirements. They have created a handbook to help with technicalities and offsetting retention and detention needs.
Within the City of Tucson, regulations apply to cisterns and all plan submittals are reviewed for zoning compliance on an individual basis (no one-size fits all permit process). However, basically the cistern size determines where it needs to be placed in your designs and whether it will need a building permit.
Cisterns built within the city need to follow the Land Use Code placement design requirements for property line setbacks applicable to accessory structures according to cistern size as described in this memo. Any cistern with over a 2:1 height: width ratio or any cistern containing over 2000 gallons requires structural review and a building permit.
Case by case scenarios include, for instance, if a cistern has a connection with a roof drain, a method is needed to insure that an overflow of the cistern does not result in water being retained on the roof. Electrical wiring installation for pumps may require building code review or permitting or installation by a licensed contractor, but this is not always the case.
A curb cut is a process by which a small portion of the bank is removed to allow water to run out of its street watercourse into a water-harvesting basin in order to provide rainwater run-off to plant materials.
Click here for information on how to apply for a permit, tips on design and informational description.
All curb cuts require a permit from the City of Tucson, Permits and Code Section, using a “Right-Of-Way Excavation Permit Application” in which designs, reviews and meetings will be required. Use these design guidelines provided by the City of Tucson.
Unlike several states, there are no Arizona statutes against rainwater harvesting. The U.S. Environmental Protection Agency does not regulate rainwater harvesting systems, but recently provided a handbook on rainwater harvesting policy and infrastructure. See comparative regulations in other states.
A variety of incentives are available as identified below:
Tax Credit in Arizona
Through 2010, the State of Arizona encourages rainwater harvesting though statewide tax credit incentives for 25% of the system. Note that a misinterpretation of the tax credit used to only give the credit to greywater systems, but thanks to efforts by Rep. Steve Farley the tax credit can now also be used for rainwater harvesting systems, and it is now retroactive to January 1, 2007. No permit is needed for residential properties for these tax credits toward rainwater harvesting (different rules apply for the greywater credit for commercial properties).
Please visit www.azdor.gov and click on "credit pre-certification" on the lefthand side of the home page and click on gray water conservation tax credit. The site includes general information and applications for corporations and individuals.
Marana - Metro Water
Metro Water District offers a $50 rebate when a resident installs a greywater or water harvesting system. Both systems capture water that is usually discarded so that it can be used for outdoor watering, thus reducing your regular water usage.
Arizona State Land Department
The Arizona State Land Department Forestry Division's Urban and Community Forestry Program’s Community Challenge Grant Program can fund the planting of trees in water harvesting earthworks, along with cistern-building and greywater-harvesting workshops.
Central Arizona Project
Central Arizona Groundwater Replenishment District Conservation Grant Program for water conservation grants up to $5,000 each available project. Projects such as a water-harvesting system for a community garden have been funded.
PRO Neighborhoods: Pima County
PRO Neighborhoods is a grants and technical assistance program for local communities based in Pima County offering small grants ranging from $500 to $5,000 to groups working together to mobilize and build upon existing talents and resources within the community.
City of Tucson
The City of Tucson offers a single family residential rainwater harvesting incentive/rebate program
. If you attend a workshop, you become qualified for a rebate. More information about the program also is available by clicking here
Additional information on residential and business rebates and incentives, including for irrigation efficiency upgrades, please click here
Rainwater Harvesting Q & A
Q: How is rainwater captured?
A: Rainwater can be directed by gutters and downspouts to cisterns to store water or more simply by earthworks. Creating earthworks is the practice of building berms or contouring slopes on a site to guide rainwater to trees and shrubs.
Q: How much rain can the desert really supply?
A: A family of three in Tucson uses an annual average of 120,000 gallons of water. With about 12 inches of rainfall per year in this region, a quarter-acre lot will receive, on average, 67,000 gallons of rain water annually-- more than enough to satisfy home exterior needs if the rainwater is kept onsite. The yearly rainfall a house of 2,000 square feet could capture is about 15,000 gallons, which could potentially be stored for use in dry seasons. Click here for rainwater capture calculation help.
Q: How does rainwater harvesting make a difference?
A: Harvesting rainwater enhances the region’s limited water supply and offsets water use and demand. Since over a third of residential potable water use goes to landscaping, switching to rainwater for vegetation needs is a simple way to reduce potable water use. Conservation of resources ensures their availability for the environment, as well as for future generations.
Q: Is rainwater safe to drink?
A: Rainwater must be purified before it is safe for human consumption. The NSF International Rainwater Catchment System Testing Program uses U.S. Environmental Protection Agency health guidelines to review rainwater harvesting materials to ensure they do not contaminate captured rainwater. Filtration is not necessary to irrigate plants or for other non-potable uses such as flushing toilets, washing clothes, and supplying water cooling towers.
Q. Do I need approval to set up a rainwater harvesting system?
A. For information about regulations and incentives, please click here.
Q: How expensive is it to harvest rainwater?
A: For the cost of a shovel, you can passively harvest rain by making sure stormwater is directed to plants and does not run off your property. Covering soil with mulch is one of the most effective ways to store water for your vegetation. Reduced water use will reduce the energy required for pumping potable utility water and save you money. Take advantage of your current resources and begin to see your roof as the top of your own personal watershed. Invest your time in observing the slope of the land, noticing where you can create depressions to slow down runoff and put it to beneficial use.
If you are ready to do more, you can connect your gutters and downspouts to cisterns, which can vary in price from under $50 for a 50-gallon barrel to several thousand dollars for larger tanks. Local resources exist for pre-made cisterns in a large price range or you can find materials to make your own for under $1,000. The Metropolitan Pima Alliance estimates a cost of $2 to $4 per gallon for a cistern system.
Community workshops and cooperatives are available for you to learn how to install storage tanks yourself. Alternatively, local technicians are available in the region to help you install a cistern.
Walter Rogers, Principal, Olsson Associates, speaks Feb. 9 at the dedication of the Arroyo Chico Urban Greenway, Si Schorr Segment, at Camino Campestre, between Randolph Way and Country Club in Tucson. Rogers explains how water harvesting capabilities are incorporated into the landscaping and pathways of this project, which is funded by the Regional Transportation Authority and the City of Tucson.
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