On October 14, 2008, the City of Tucson, Arizona adopted the country’s first commercial rainwater harvesting ordinance. Beginning June 1, 2010 all new commercial construction must meet the following requirements:

1. Meet 50% of landscape irrigation needs using harvested rainwater
2. Prepare a site water harvesting plan and water budget
3. Meter outdoor water use
4. Use irrigation controls that respond to soil moisture conditions at the site.

Rainwater harvesting reduces the demand and costs for potable water, while minimizing damage from flooding and erosion. In arid climates like Tucson’s, the use of harvested rainwater can be an especially effective method of water conservation, while also reducing a property’s water costs.

The City is focusing outreach and education efforts on developers and designers, who need to understand how the policy will affect the design process early on. A technical advisory group made up of landscape designers, civil engineers, maintenance workers, and others was formed to create the development standards, which lay out the technical specifications of implementation. A presentation was created to inform developers of system, structure, and plant options. One presentation was given in March 2010 and several others are planned for the future. Outreach is also done through the Internet and email.

The Mayor-In-Council appointed a stakeholder group to provide input during the development of the ordinance. The group has helped with outreach and education by engaging as many as fifty separate community interests, including non-profit environmental organizations, builders, developers, water harvesting experts, and more.

The City originally stated a 100% rainfall capture requirement, but with public input, decided that amount wouldn’t be feasible. The requirement was reduced to 50%, based on staff analysis that indicated this could be achieved with passive harvesting techniques alone.

The City faced some opposition from apartment owners and large developers, who viewed the policy as an added cost in the design, implementation, and maintenance stages. The City is continuing to work with these stakeholders to address their concerns.

There is some concern about the accuracy of water needs, since effective rainfall differs from measured rainfall, and because Tucson does not have a water use guide for plants like California’s WUCOLS (Water Use Classifications of Landscape Species).

Water conservation is generally supported in Tucson, and water harvesting in particular is already common on the residential level.

The ordinance goes into effect June 2010, and will be monitored but not enforced for the first three years. The policy requirements will not apply during a drought, which the City is currently facing.

The City is using existing resources to fund the development of this project. Grants and usage fees from the conservation program fund are used to set up demonstration sites, which help subsidize costs for developers, encouraging early adoption, experimentation, and support. They hope to continue funding these sites for the next few years. A grant was also given to the water department to develop the presentation package for public outreach and education.