After 90 Years of Reusing Reclaimed Water in Arizona, What’s in Store?

Back to AWR Fall 2016

by Chuck Graf, Arizona Department of Environmental Quality

Payson Green Valley Lake

Arizona has a long history of putting treated wastewater to beneficial use, in fact, 90 years of history. In 1926, at Grand Canyon Village on the South Rim, the first wastewater treatment plant in the US built specifically for water reuse began supplying water for power generation, Santa Fe Railroad steam locomotives, and flushing toilets. The local power station and steam locomotives are long gone, but reclaimed water continues to be used to this day for landscape irrigation and, yes, for flushing toilets.

It wasn’t until 1972, though, that the Arizona Department of Health Services adopted the state’s first rules governing reclaimed water quality and use, some of the first in the nation. Fast forward another decade to 1983, when Arizona’s largest treatment plant, at 91st Avenue in Phoenix, began supplying about 60 million gallons per day of reclaimed water to the Palo Verde Nuclear Generating Station west of Buckeye. Palo Verde, the largest nuclear power generator in the US, is unique in the world for being wholly cooled by reclaimed water.

In 1999, the Arizona Department of Environmental Quality (ADEQ) received clear authority from the Legislature to regulate the beneficial reuse of reclaimed water, and in 2001, ADEQ transformed the program by adopting rules that foster reuse while protecting water quality and human health. Independently, the Arizona Department of Water Resources (ADWR) was administering a program that allows accrual of credits for recharge of treated wastewater in Active Management Areas to offset limits on groundwater pumpage. These programs, which spurred a dramatic increase in the volume of wastewater treated for reuse and recharge, established Arizona as a national leader in the regulation and practice of reclaimed water reuse.

Three regulatory components mesh to create Arizona’s wellregarded reclaimed water program. First, as part of its aquifer protection program, ADEQ sets stringent treatment standards for new and expanding wastewater treatment plants. These standards include reduction of total nitrogen to below drinking water limits and removal of fecal coliform bacteria, an indicator of pathogens, to a routinely non-detect level. Second, water quality standards are designated in rule for five reclaimed water quality classes, which are tied to allowed end uses based on human health protection. Last, an uncomplicated but effective system of permits for end users has stimulated the expansion of safe reclaimed water use.

So, how is Arizona doing? Astonishingly well, I think. Of Arizona’s one hundred largest wastewater treatment plants, 93 percent distribute reclaimed water for reuse. Almost 60 percent of the plants deliver Class A+ reclaimed water, the best quality of reclaimed water under ADEQ’s classification scheme.

If we look at reuse volumes, the numbers are also astonishing. According to an ASU study, 82 percent of all treated wastewater generated within the Phoenix Active Management Area (60 percent of Arizona’s population) is beneficially reused or recharged.

With this much reuse already occurring, what are the trends? First, communities currently reusing reclaimed water often have excess water in the winter when turf and landscape demands are reduced. Consequently, expect to see more recharge of excess water at new or expanded recharge facilities to gain credits from ADWR. Second, expect to see a transition from lower-valued uses, such as turf irrigation, to industrial or other highervalued uses. Third, expect to see more reuse by smaller communities. Currently, only 40 percent of the 200 or so smaller wastewater treatment plants under ADEQ permit are distributing reclaimed water for reuse. Although volumes might be small, the supplies may be critical in rural areas in view of drought and other drivers. Also, expect to see more plans for multi-purpose community enrichment projects, such as the Gilbert Riparian Preserve and Payson Green Valley Lake. In this vein, reclaimed water is becoming so valuable that riparian areas dependent on its flows are coming under pressure. Therefore, expect to see more vocal support for considering environmental needs and riparian enhancement as a valid end use for reclaimed water. Finally, there is a groundswell of interest by communities in determining whether potable reuse can be a viable part of their water portfolios.

Time has marched on since 2001 when ADEQ last adopted reclaimed water rules. New concerns and needs have arisen, and treatment and monitoring technologies have advanced impressively. For this reason, on January 1 of this year, ADEQ opened a docket with the Secretary of State to revise its reclaimed water rules. ADEQ received more than 300 comments during informal listening session workshops held around the state earlier this year. ADEQ anticipates revising the rules in two or three installments, aiming for adoption of the first installment, after formal public comment, at the end of 2016 or in early 2017. This first installment will clarify ambiguities, correct errors, and fold some less complex technical and administrative improvements into the rules. It will also introduce a new structure to the rules, in which regulatory provisions for the current categories of reused waters—reclaimed water and gray water—will reside under the umbrella of a new designation—recycled waters. Followup rulemaking will address more complicated technical issues. such as reviewing the suitability of the reclaimed water quality standards in light of current knowledge and considering the adoption of criteria for potable reuse if warranted by the current state of science and technology.

To stay on top of ADEQ’s rulemaking effort and be notified of opportunities for public comment, please send an email to