Phoenix’s first advanced water purification plant, part of the city’s Pure Water Phoenix program, has officially hit the halfway point in construction, according to city officials. Crews recently filled a roughly 1 million-gallon treatment basin as part of system testing, a very visible sign that the long-planned upgrade is moving into its next phase. The goal is for the plant to eventually turn treated wastewater into water that can be reused for drinking once testing and permitting wrap up.
Images from news wires show workers filling the basin last week, and local coverage reports the project is roughly three years away from producing drinkable water. Reuters distributed photos of the fill and system tests, and broadcaster KTAR reported that timeline.
What the Plant Will Do
The Cave Creek Water Reclamation Plant is being retrofitted with advanced purification steps including reverse osmosis and ultraviolet advanced oxidation. The upgraded facility is designed to produce nearly 7 million gallons of purified water a day, which officials say is enough to serve roughly 25,000 households. According to the City of Phoenix, the plant will go through a one-year demonstration period where the product water is closely monitored and used to recharge groundwater before any direct addition to the drinking water system. Much of the existing plant infrastructure is being repurposed to speed construction and keep costs in check.
Regulatory Checkpoint
The Arizona Department of Environmental Quality has opened a public comment period on a significant amendment to the plant’s aquifer protection permit, with comments accepted March 12 through April 10, 2026. ADEQ outlines an 8.0-mgd treatment train and the advanced treatment components that must meet aquifer protection standards. The public comment window will serve as an early regulatory test for the project’s proposed groundwater recharge and reuse plan.
Funding and a Regional Push
Federal funding has given the Pure Water Phoenix program a serious tailwind. The Bureau of Reclamation’s WaterSMART pages outline roughly $200 million for water-reuse projects in the Colorado River Basin, including a $179 million award for Phoenix’s North Gateway facility. The state’s rulemaking for direct potable reuse was approved in 2025 and now sets the permit framework utilities must meet. Regulators say these investments are meant to reduce dependence on the Colorado River. The Arizona Capitol Times reports officials predicting that advanced purification could scale to tens of millions of gallons of water a day over the next decade.
What to Expect Next
City officials say construction at Cave Creek began in August 2024 and that the plant will enter a demonstration phase in 2027, with purified water folded into Phoenix’s supply in later years after testing and permitting are complete. As the city runs operational tests, officials plan tours and public outreach to build trust in direct potable reuse and to show off the monitoring safeguards that will be in place.
The decision to revive the Cave Creek site was covered earlier, and this latest construction milestone signals a shift from planning to hands-on testing for Phoenix’s water future.
