FAQ: Water in Arizona
Published: 10/21/2026
How does Arizona use water?
For generations, the work of Arizona leadership to ensure a stable water supply has allowed families and businesses to operate without concern. With the shortage of the Colorado River, there is increased attention and more questions from residents and others around the country and world on Arizona’s and Greater Phoenix’s water situation.
The frequently asked questions and answers below, some of which were compiled from a list of audience questions asked at the Greater Phoenix Economic Council’s August Regional Report, touch upon basic definitions, the Colorado River, advanced water purification, desalination, importation and more.
1. What is an acre-foot?
An acre is 43,560 square-feet, about 75% the size of a football field (including end zones). An acre-foot of water is 325,851 gallons, or enough to fill an acre of land with one foot of water.
The Arizona Department of Water Resources estimates that one acre-foot can serve three single-family houses for a year.
Large bodies of water like the Colorado River are measured in quantities of million acre-feet, abbreviated to MAF. In context: The Colorado River Compact allocates 7.5 MAF/year — 7.5 million acre-feet per year, over 2.4 trillion gallons — to the Upper Basin (consisting of Colorado, New Mexico, Utah and Wyoming) and 7.5 MAF/year to the Lower Basin (Arizona, California and Nevada). Mexico is legally allocated 1.5 MAF/year by a bilateral treaty.
2. How is water used by each sector in Arizona?
In Arizona, water usage is roughly broken down as:
- 74% agriculture
- 20% municipal
- 6% industrial
Some examples of agricultural water use are irrigated farming, crop growth, livestock and dairy. Municipal uses include residential homes, golf courses, parks and more. Industrial uses include manufacturing, steel production, data centers and power generation, among others.
3. Why is the Colorado River in a shortage?
A variety of factors have led to the shortage on the Colorado River, ranging from early-20th century miscalculations to the long-lasting drought in the 21st century.
The 1922 Colorado River Compact overallocated water. The agreement was under the assumption that river flows would average 16.4 MAF/year, but the actual flows were about 14.6 MAF/year from 1906-24, according to Congress.
Further affecting river flow is the historic 25-year drought in the southwest. There has been less precipitation and less runoff that reaches the rivers and stays in reservoirs due to rising temperatures that have changed patterns of evaporation and snowpack melt. Additionally, the dry soil soaks more rainwater than it would if it were consistently receiving precipitation, preventing that water from reaching the river.
Sedimentation, due to causes including natural erosion and wildfires, has also affected the amount of water that enters and is retained in reservoirs.
These are just a few reasons that there is less water in the Colorado River today than in the past.
4. What is Arizona doing to address its water supply?
The work continues from before statehood. Past generations of leadership have invested in activities ranging from the establishment of Salt River Project (SRP) and Central Arizona Project (CAP) to the creation and reclamation of canals to the construction and renovation of dams. Arizona has 12 MAF of water stored in reservoirs and underground, and uses less water annually today than it did in the 1980s, thanks in part to modern conservation and shifts from an agricultural-based economy to one that is more industrial-based.
Arizona continues to follow standards set by the 1980 Groundwater Management Act, which prohibited bringing new irrigation acres into production, required a permit or right to pump groundwater, imposed mandatory conservation for all agricultural, municipal, and industrial water users, and established the legal and physical infrastructure for a 100-year assured water supply.
The legislature has funded groups like the Water Infrastructure Finance Authority (WIFA), which has spent hundreds of millions of dollars on water projects across the state. In January 2025, Gov. Katie Hobbs invested $60.3 million toward conservation, advanced technology and infrastructure.
Individual cities and towns continue to invest in and diversify their individual water portfolios through conservation, water purchases, advanced water purification and more. Additionally, SRP is in the process of multiple water projects including an interconnection with CAP and a potential expansion of Bartlett Dam.
5. How would renovations to Bartlett Dam help provide additional water?
Bartlett Dam needs to either expand, have sedimentation removed, or both. Doing so will allow SRP to maximize water storage during wet years that can serve as a fallback for dry years.
The clearest example is 2023. It was a wet enough year to fill Bartlett Reservoir, but the dam wasn’t big enough to contain all the water. Excess water had to run off, wasting our resource that would have otherwise been useful during times like this, when Arizona is set to have a reduced allocation of Colorado River water.
SRP is undergoing a feasibility study for an expansion that would raise Bartlett Reservoir’s water surface elevation by 100 feet, increasing capacity to provide water to 1 million households for a year. This would help restore capacity that has been lost to sedimentation on the Verde River.
6. What is “toilet to tap”?
“Toilet to tap” is an inaccurate colloquial term to describe an advanced process of water purification. This terminology evokes imagery of drinking sewage water; that is not the case. In reality, this water goes through several steps of reverse osmosis, ultraviolet advanced oxidation, and other filtration and disinfection that clears the water of everything ranging from dust and debris to microbiomes and harmful chemicals and pathogens, ensuring the water is as clean or cleaner than if it were to have pumped from a riverbank or aquifer.
There are currently no potable advanced water purification (AWP) facilities in use in Greater Phoenix. Scottsdale has a non-potable AWP facility, and there is a potable facility under construction in Phoenix.
7. Can we pursue desalination?
It’s possible, but it’s expensive. Cost is a larger factor than technical ability, because it is far more expensive than traditional water methods, AWP or conservation.
With that said, work is underway. SRP and CAP are in discussion with San Diego on an exchange program for the southern California city’s excess desalinated water. Desalination will likely become a tool in Arizona’s water portfolio, but it is a longer-term solution due to the cost of water and need for an exchange mechanism.
8. What about importation? We have a vast network of pipes across state and international lines to import gasoline — why not water, too?
The cost of water would need to become exponentially more expensive to cover the cost of infrastructure.
For comparison, the average price of a barrel of crude oil, about 42 liquid gallons, was $76.05 from 2021-25, according to Macrotrends.net. Municipalities pay about $512 per acre-foot (325,851 gallons) of Colorado River water, according to the Natural Resources Defense Council. Based on that pricing, the equivalent of a barrel of water — 42 liquid gallons — costs municipal users about $0.07. Matching the necessary infrastructure to import water would cause prices to skyrocket.
If comparing to natural gas pipelines, there is no one-to-one comparison because water is much heavier than gas.
9. If the Colorado River allocation is reduced, how are we going to prevent exhausting the Salt and Verde rivers?
For decades, Arizona has stored water underground and in aquifers including the Granite Reef Underground Storage Project (1994) and the New River-Agua Fria Underground Storage Project (2007) in preparation of the potential of a moment like this. This will help supplement the decreased allocation of Colorado River water and ensure that we are not overconsuming the Salt and Verde rivers.
Arizona faces a reduction of at least 760,000 acre-feet if the U.S. Department of the Interior’s Record of Decision and the Lower Basin solution are implemented. The state has sufficient water stored to manage the decrease and support our other water sources while planning for future reclamation, conservation and new water tactics. The river allocation will be renegotiated every two years across the next 10 years.
10. How will building these new water systems affect water prices for consumers?
This is at the core of the water discussion in Greater Phoenix. We will not run out of water, but water will likely become more expensive for consumers and businesses. The region’s and state’s ability to implement new systems for storage and reclamation, conserve water at the individual and corporate levels, and form new agreements with public and private groups in other states will dictate how water pricing will change.
11. Water is getting more expensive and supplies are tightening. Why don’t we hear more about conservation?
Conservation is happening in Arizona, but much of it takes place at a large scale, where it’s less visible day-to-day. This includes water reclamation plants at companies like Intel and TSMC Arizona, and long-term investments in water conservation from cities, towns and providers. Eighty-nine percent of water in the waste stream gets reclaimed.
Because there are mandatory conservation requirements for municipal water providers, water providers are responsible for determining the optimal water conservation measures in their service areas. Cities and other water providers have relied upon voluntary measures like tiered water rates and incentives to remove grass or use water-efficient fixtures homes and business. Each water provider must have a drought plan, which contain mandatory residential restrictions at deeper shortage levels than Arizona currently faces.
Because of the Groundwater Management Act, which made Arizona first in the Colorado River basin to impose mandatory conservation, Arizona got a head start and has been able to implement conservation gradually over time. As a result, there are currently no mandated restrictions for residential water use in Greater Phoenix, which may make it seem like it doesn’t impact us as residents; however, individual choices do matter. Cities have seen reduced water uses, including Phoenix residential water use per person drop from roughly 140 gallons per day in 1990 to 90 gallons per day in 2025. Glendale’s municipal water use dropped by 19% during a Stage 1 Drought Watch, according to YourValley.net.
The Arizona Department of Water Resources provides tools and resources to conserve water, including landscaping, technology and kids’ education, and some cities and towns offer programs or even incentives to decrease water use. Contact your local provider or municipality to learn more.