A.R.S. 45-454: Arizona's Exempt Well Rule (35 GPM)

When you buy raw land in Rio Verde, Cave Creek, or any part of rural Arizona with no water utility, the well is what makes the lot buildable. A.R.S. 45-454 lets a single home drill its own well without the heavy permitting that governs large groundwater users. It does this by defining a category called the exempt well. The line that defines it is a pump size: 35 gallons per minute.

What makes a well exempt

The statute exempts small non-irrigation wells from most of the groundwater code based purely on pump capacity. The number is the whole test.

Withdrawals of groundwater for non-irrigation uses from wells having a pump with a maximum capacity of not more than thirty-five gallons per minute.

A pump rated at or under 35 gallons per minute clears the bar. Anything above it does not. A typical single-family home uses far less than that over a day. So the threshold is sized to cover ordinary home use, watering a small yard, and a few animals. It keeps large farm and commercial pumping inside the regulated system. The exemption is from the permit-and-allotment rules that control bigger wells, not from every rule. That last point is what landowners most often misread.

What this means for you

If you are building a single custom home on rural Arizona acreage with no water line, an exempt well is almost certainly your path, and you size the pump at or below 35 gallons per minute to stay exempt. That keeps you out of the regulated-user process and lets a licensed well driller put in a domestic well for the house. A worked example: you own five acres in unincorporated Maricopa County near Rio Verde with no utility water, so you drill an exempt well with a 25-gallon-per-minute pump to serve the home, and you do not need a groundwater right or pumping allotment to do it.

Exempt does not mean unregulated. You still file a notice with the Arizona Department of Water Resources (ADWR) before drilling. The well still has to meet construction standards. And inside an Active Management Area, the regulated zones around metro Phoenix and Pinal, extra conditions and transport limits apply. Exempt status also does not promise that water is down there or that it is clean. On a vacant lot the depth, yield, and quality are real unknowns you confirm before you build, not after. If one well will serve more than one home, that setup is governed separately by a shared well agreement.

How this connects to the rest of the law

The well exemption is step one; the paperwork is step two. Before any drilling, you file the notice covered in A.R.S. 45-596 , which is the Notice of Intention to Drill, and the lower $100 fee in that section is reserved for exactly the small domestic exempt wells defined here. On a buildable-land checklist the well sits next to your septic system, which is why your lot also needs a percolation test to confirm the soil can absorb a septic drain field. For the full rural picture, see what you need to build on rural land in Rio Verde , the drilling-notice walkthrough in what is an ADWR notice of intent to drill a well , and the multi-home case in what is a shared well agreement in Arizona .

Full text and source

Read the current version, including the Active Management Area conditions and reporting duties, on the legislature's site: View A.R.S. 45-454 on azleg.gov .

Because the exemption turns on pump capacity and varies inside Active Management Areas, confirm your pump sizing and any local AMA limits with ADWR before you commit to a well as your water source.