Chapter 2.1
Floodplain and River Corridor Land Use

• ALL
• Remove Code Barriers
• Create Incentives
• Fill Regulatory Gaps

Rainwater Harvesting

INTRODUCTION

Under current and anticipated conditions associated with climate change, many communities’ access to water will be stressed.[1] Population growth and development will increase demand on municipal water systems, while climate change will decrease and/or make more inconsistent available supplies of freshwater.[2] In addition, many communities will experience “precipitation whiplash” in which they experience extreme dry followed by extreme wet conditions (and vice versa) in a very short time frame.[3] Precipitation whiplash can greatly stress a community’s ability to meet water demands.

Rainwater harvesting (RWH) is the act of utilizing a passive or active collection system to capture and store rainwater for non-potable uses like plumbing and landscaping, or for potable uses like consumption.[4] Typically, RWH systems comprise three interconnected components; a catchment, normally a roof top, which makes first contact with the rainwater; a conveyance or downspout, which directs the water from the catchment; and a cistern for storage, which holds the water.[5] Systems may also have a filter and pump, depending on the intended use.[6]

For the most part, the federal government does not regulate rainwater harvesting. Rather, individual states and local governments regulate the collection and use of rainwater.[7] State-level rainwater harvesting regulations and policies vary widely.[8] Only a few states have enacted all-encompassing or systematic regulations encouraging the collection and use of rainwater.[9]

Ordinances incorporating RWH have several options. Some local governments have amended their development code to require that new development projects implement a RWH system or rainwater catchment plan. Additionally, local governments may set target standards for rainwater collection. Such standards may be based on the size of the catchment area (for example, requiring the catchment area to be 85% of rooftop run-off), may ban private covenants from restricting RWH systems, or may require a certain percentage of all on-site rain be harvested. Municipalities that do not require rainwater collection systems, but simply encourage them, may consider offering rebates for RWH system installation through their municipal water provider.

EFFECTS

Some of the primary benefits of rainwater harvesting include; increased access to water, easing the burden on municipal water sources, increased resilience to unforeseen precipitation fluctuations, and decreasing water utility costs. Residential outdoor water use in the United States accounts for more than 9 billion gallons of water each day, mainly for landscape irrigation.[10] Adopting rainwater harvesting systems can reduce the amount of water typically provided by municipal systems, while reducing consumer costs.[11]

Additional environmental benefits include decreasing sediment erosion from stormwater runoff and decreasing harmful contaminants, such as fertilizer, sediments, and pesticides, from running off into waterways and stormwater systems.[12] RWH does this by “reduc[ing] stormwater runoff volume up to 20% in semiarid regions.”[13]

One challenge involved with RWH comes from a study that indicated, “[RWH] rebate recipients were simply adding additional, new landscaping to be watered with harvested rainwater, rather than reducing their overall consumption.”[14] Therefore, local governments may consider offering other incentives for overall reductions in water consumption or supplementing landscaping standards to require overall reduction use as part of RWH incentives.

EXAMPLES

Santa Fe County, NM

In 2016, Santa Fe County amended its Sustainable Land Development Code (SLDC) to require that RWH systems be implemented for all new residential and all new or renovated non-residential development projects.[15] Santa Fe County’s rainwater catchment ordinance mandates that residential RWH systems be designed to capture rainwater from a minimum of 85% of the roofed area.[16] Additionally, the ordinance states that cisterns for residential primary or accessory structures shall be connected to a pump and a drip irrigation system to serve landscaped areas.[17] The ordinance specifies further that if captured water is used for domestic purposes, appropriate plumbing and pumps may be used to convey that water to the point of use.[18] Santa Fe County’s ordinance also outlines separate and stricter RWH standards for non-residential structures. For non-residential structures, systems shall be designed to capture rainwater from 100% of the roofed area.[19]

To view this provision, see Santa Fe, NM, Sustainable Land Development Code § 7.13.11.7. (2016).

Tucson, AZ

In October 2008, Tucson, AZ became the first city in the United States to require developers of commercial properties to harvest rainwater for future landscaping use.[20] Tucson amended its Unified Development Code, mandating that new commercial development projects and site plans include a RWH plan and that 50 percent of landscaping water demand be met using the harvested water collected through either active or passive rain water harvesting.[21] The ordinance requires that the proposed implementation plans show how any combination of capture, conveyance, storage, and distribution will be utilized on-site to harvest rainwater. In addition, the plan must include a water budget calculating the estimated volume of water required yearly for all site landscaping detailed in the development plan and water metering of all on-site landscape water through either a separate water meter connected to the main water supply or an irrigation sub-meter.[22]

Tucson Water, a department of the City of Tucson, operates as the city’s Public Water Utility serving residential, commercial, and industrial customers.[23] In addition to the city amending its development code, Tucson Water implemented a rebate program for residential uses to incentivize local investment in residential RWH systems. Residential users qualify for the rebate by attending a mandatory workshop focused on passive and active RWH systems for residential ownership.[24] Tucson’s program offers up to $2,000 for active systems and up to $500 for all passive RWH systems.[25] Tucson has provided funding for the rebate program by charging users a $0.25 fee on their monthly water bill.[26]

To view the provision, see Tucson, AZ, Tucson Code § 6-182,183 (2008).

ADDITIONAL EXAMPLES

Albuquerque, NM, Code of Ordinances § 6-1-1-8(c) (2019) (prohibiting restrictive covenants barring the use of rain barrels or other water harvesting devices, provided such devices adequately protect the public's health, safety, and welfare).

Flagstaff, AZ, City Code § 10-50.60.070 (2019) (requiring RWH system when non-drought tolerant plants are installed that are not listed on the city’s landscape plant list; if native/drought-tolerant plants are installed and passive rainwater harvesting techniques are utilized, or landscape water demand can be met through other sources of non-potable water, a RWH system is not required).

Yavapai Cty., AZ, Planning and Zoning Ordinance § 512(I) (2017) (allowing a rainwater harvesting system component and/or up to a three thousand (3000) gallon enclosed water storage tank).

Orlando, FL, Code of Ordinances § 60.228 (2019) (requiring all landscape plans to achieve the Minimum Required Landscape Score, including calculations demonstrating the volume of water required and volume provided by rainwater harvesting).