Every buyer who looks at land south of Tucson asks about water before they ask about anything else. Fair. It's the desert. But most of what people "know" about water down here is a headline from Phoenix or Pinal County that doesn't apply to the Tucson basin. So here's how it actually works, with a link for every claim so you can check my math.

The short answer

No, and the paper trail is long. Tucson gets its water from three sources - Colorado River water through the CAP canal, reclaimed water, and groundwater - and for years it has bought its full river allocation and banked what it doesn't use in the aquifer under Avra Valley and south Tucson. When the Colorado River shortage hit, Tucson's water director told NPR the shortage wasn't expected to affect the Tucson basin because of that bank.

The real 2026 story is the river, not the aquifer. The seven basin states still haven't agreed on how to run the Colorado after this year, and Arizona has offered to take a 27% cut to its allocation in those talks. That matters for the city's long-term planning. It matters far less for someone buying acreage on a well south of town, and the rest of this piece is about why.

Two different questions

"Is there water?" is really two questions, and they have different answers depending on what you're buying.

If you're buying acreage to put a home on, you're in the world of private wells, and the process is a filing, not an approval. If you're buying land to split into many small pieces, you're in the world of the 100-year assured water supply, which is a state program with published rules. People mix the two up constantly. Don't.

Wells: what the law actually requires

Domestic wells that pump up to 35 gallons per minute are exempt under Arizona statute. That 35 is a ceiling, not a requirement. You file a Notice of Intention to Drill with the Arizona Department of Water Resources, use a licensed driller, and register the well when it's done. No certificate, no hydrology study.

Yield is where people panic unnecessarily. Rural Arizona homes don't run straight off the well. The well fills a storage tank and a booster pump runs the house at full pressure, which is exactly what the University of Arizona's well guide recommends where sustained yield is modest. Even 3 gallons per minute, the statute's own definition of a struggling well, puts over 4,300 gallons a day into a tank. A typical Tucson-area household uses about 300.

One more thing buyers miss: the 100-year rule doesn't attach to every piece of land. Under state law a "subdivision" is six or more parcels under 36 acres each. Parcels of 36 acres and up sit outside that definition, which is why so much of the ranch country down here is cut at 36 and sold on wells.

The 100-year rule, and where it's paused

You've read that Arizona stopped approving new subdivisions on groundwater. That happened in the Pinal Active Management Area in 2021 and the Phoenix AMA in 2023. No such determination has been made for the Tucson AMA, which covers the basin from Marana down past Green Valley. Here the program still runs on its published criteria: 100-year physical, legal and continuous availability, adequate quality, financial capability, plan consistency, and a depth-to-water limit of 1,000 feet.

Two things moved this year. In April, the Maricopa County Superior Court blocked ADWR's "unmet demand" rule, the one that had frozen approvals around Phoenix. And ADWR is rebuilding its Tucson-area groundwater model, targeted for 2027. That model is the thing to watch if you're planning a subdivision south of town.

There are three recognized ways to make a 100-year showing: a certificate backed by CAGRD replenishment enrollment, a commitment of service from a designated water provider, or renewable supplies and long-term storage credits dedicated to the project. Designated providers already exist in the corridor. Sahuarita Water Company holds a 100-year designation, and the precedent is right there on the ground: more than 4,000 homes at Quail Creek got their assured supply approvals, and the whole Town of Sahuarita, 34,000-plus people, was built under the same program.

What's actually underneath us

This is the part nobody puts in a listing, and it's the strongest part of the story.

What to check before you buy

  • Any well's depth, level and yield: ADWR's well registry. Every registered well in the state is in there.
  • Whether a parcel sits in a designated provider's service area, or under a certificate: Pima County's assured water supply map.
  • The state public report for any parceled land you're buying. It has to disclose the water situation in plain language. Read it before the earnest money goes hard.

The questions people actually type into Google

Is Tucson running out of water? No. The city runs on three sources, banks its unused Colorado River water underground, and the water director has said the river shortage isn't expected to hit the Tucson basin. The open question is how much river water Arizona keeps after 2026, which is a planning issue for the city, not a today problem for a rural well.

Where does southern Arizona get its water? The Colorado River through the CAP canal, treated reclaimed water, and groundwater. South of Tucson the biggest users, the Mission mine and the pecan orchards, moved most of their demand onto river water, and three recharge projects put water back into the aquifer.

Can I drill a well on land south of Tucson? On most rural acreage, yes. A domestic well up to 35 gallons per minute is exempt: you file a notice with ADWR, use a licensed driller, and register it. No certificate, no hydrology study.

Does the Arizona groundwater pause apply here? No. The pauses were in the Pinal and Phoenix management areas. The Tucson AMA has had no such determination, and a court blocked the Phoenix rule in April 2026 anyway.

What should I check before I buy? The parcel's well records in the ADWR registry, whether it sits in a designated provider's service area on the Pima County map, and the state public report for any parceled land. All three are linked below.

If you're looking at acreage south of Tucson and the water question is the thing holding you up, send me the parcel number. I'll pull the well records and the county map and tell you what's there. No pitch, just the answer.

Hudson Robison
Designated Broker, The Broker Reserve

Sources

  1. A.R.S. § 45-454, exempt wells · ADWR, exempt wells · S.2063, 3-gpm threshold
  2. Statutory "subdivision" definition, Dunaway Law Group
  3. ADWR, Assured and Adequate Water Supply overview
  4. Snell & Wilmer on the Phoenix AMA pause · Arizona Daily Star, 1,000-ft limit
  5. WRRC, Pinal AMA determination (2021)
  6. Arizona Mirror, rule blocked April 2026 · ADWR Tucson groundwater model
  7. ADWR list of designated providers · Sahuarita Water Company
  8. Pima County assured water supply map and CAGRD
  9. Arizona Daily Star, Quail Creek approvals · Sahuarita population
  10. 72 Fed. Reg., Statement of Findings (2007) · S.437, Arizona Water Settlements Act
  11. Arizona Daily Star, Mission mine on CAP (2009) · Arizona Daily Star, pecan pipeline (2020) · Freeport-McMoRan, Twin Buttes
  12. University of Arizona Cooperative Extension, AZ1581 · Arizona Daily Star, household use
  13. KGUN 9, the future of water for Tucson and Marana residents · NPR, Tucson's banked Colorado River water · AZPM, what Colorado River cuts could mean for Tucson's water supply (March 2026)
  14. Town of Sahuarita, Pima Mine Road Recharge · Community Water Co., Project Renews · Green Valley Pecan, groundwater savings facility · Arizona Daily Star, USGS subsidence findings

Compiled from the public sources linked above, believed reliable but not guaranteed. Nothing here is a guarantee of water availability, well yield or any regulatory outcome; assured water supply determinations are made solely by the Arizona Department of Water Resources. Equal Housing Opportunity.