Arizona buyer question
How does Arizona's 100-year water rule affect where homes are built?
Arizona ties new subdivisions to a long-term water supply. Here's how the rule works, where it applies, and what to check on the home you're considering.
Two ways to start
- Search homes by payment
Create your free account to see all homes for sale that fit the monthly payment you're comfortable with, each with its actual property taxes, HOA dues, estimated homeowners insurance, and mortgage insurance when it applies, plus its own estimated closing costs and APR disclosure.
Opens a third-party home search site. Payments shown there are estimates to help you search, not a loan offer or rate quote. Your actual payment depends on price, down payment, credit, taxes, insurance, HOA, and loan program.
- Get pre-qualified (Apply now) (opens in a new tab)
Get pre-qualified with Pam Messina at Rebel Rate Mortgage. Once you're pre-qualified, Pam can update the maximum monthly payment and total funds to close in your home search, so the homes you see match what you qualify for. If you'd like, she can also give you a free, no-obligation introduction to a real estate professional so you can start touring homes.
Opens Rebel Rate Mortgage's secure online application (my1003app.com) in a new tab. Pre-qualification isn't a loan approval or a commitment to lend; approval depends on underwriting, verification of your information, and the property.
Applications are handled by Pam Messina, NMLS #245626, Rebel Rate Mortgage, Inc. (NMLS #2571369).
The short answer
Quick answer: Inside Arizona's active management areas, including the Phoenix, Tucson, Prescott and Pinal areas, a developer can't sell lots in a new subdivision without a certificate of assured water supply or a commitment from a provider designated as having one. That means water physically, legally and continuously available for at least 100 years (A.R.S. §45-576). Outside those areas the rules differ.
Source: Arizona Revised Statutes §45-576, §45-411 and §45-108 (retrieved October 27, 2026). Last updated .
What is an active management area?
Arizona's groundwater law created active management areas where groundwater use is regulated most closely. A.R.S. §45-411 established the four initial ones: Tucson, Phoenix (including the east and west Salt River Valley, Fountain Hills, Carefree, Lake Pleasant, Rainbow Valley and Hassayampa sub-basins), Prescott (Little Chino and upper Agua Fria) and Pinal. Check the Arizona Department of Water Resources maps for the current boundaries before relying on any one address.
How the assured water supply rule works
Under A.R.S. §45-576, a person who wants to sell or lease lots in a new subdivision inside an active management area must either:
- get a certificate of assured water supply from the director of water resources, or
- get a written commitment of water service from a city, town or private water company the director has designated as having an assured water supply.
The city, town or county can approve the plat only after one of those, and the plat must note which one. The state real estate commissioner can't issue the public report that authorizes sales without it. The statute defines the supply as water of adequate quality that will be continuously available for at least one hundred years.
What changes outside active management areas?
Outside active management areas, A.R.S. §45-108 requires a developer to submit the subdivision's water plans for an evaluation of whether the supply is adequate for 100 years. In most places, a report that the supply is inadequate doesn't block sales by itself. Instead, A.R.S. §32-2181 requires promotional material and sales contracts to display the water report or an approved summary. Some counties and towns have adopted a stricter option that makes an adequate supply a condition of approval.
Create your free account to see all homes for sale that fit the monthly payment you're comfortable with, each with its actual property taxes, HOA dues, estimated homeowners insurance, and mortgage insurance when it applies, plus its own estimated closing costs and APR disclosure.
Opens a third-party home search site. Payments shown there are estimates to help you search, not a loan offer or rate quote. Your actual payment depends on price, down payment, credit, taxes, insurance, HOA, and loan program.
Lot splits and wells
These rules attach to "subdivisions," which Arizona law defines as land divided into six or more lots, parcels or interests (A.R.S. §32-2101). Homes on land divided into fewer lots, or older parcels outside any subdivision, may rely on a private well or a small water company instead. If the home isn't on a city or town water system, ask:
- Who provides the water, and is the provider designated as having an assured or adequate supply?
- If there's a well, who owns it, is it shared, and what do well records and a water test show?
- Is the home on septic instead of sewer? See your inspection and county records.
What to check for the home you're considering
- New construction: ask the builder for the subdivision public report, which states the water supply and provider.
- Resale: find the water provider on a recent bill, then confirm its designation with the Arizona Department of Water Resources.
- Any home: read the Seller's Property Disclosure Statement, which covers water source and wells.
Water and your monthly budget
Water bills, well upkeep and any water-related HOA or district charges are part of the cost of owning. Comparing homes by their full estimated payment helps you see what fits before you fall for a home.
A free account shows every home for sale that fits the monthly payment you're comfortable with, each with its real property taxes, HOA dues, estimated homeowners insurance, and mortgage insurance when it applies, plus its own closing cost estimate and APR disclosure.
Searching is free, and we never sell your information or pass it to other lenders or marketers. Only Rebel Rate Mortgage, Inc. contacts you, and only about your own search.
Related: new construction: what to check · moving to Arizona · SRP or APS for electricity · more questions.
General information, not legal advice. Water designations and county rules change; confirm with the Arizona Department of Water Resources and the local jurisdiction.
What clients say about Rebel Rate Mortgage
Rebel Rate Mortgage makes it effortless for my clients to utilize their services. Excellent service, rates and professionalism.
Robert M. · Google review
Review mentions Pam Messina, NMLS #245626
Highly recommend Rebel Rate Mortgage! Pam and Josh were amazing to work with. They were friendly, knowledgeable, and made the whole process easy from start to finish. Couldn't have asked for a better experience!
Jeb B. · Google review
Review mentions Daryle Messina, NMLS #183491
Review mentions Pam Messina, NMLS #245626
I had a great experience working with Daryle and Pam for my first mortgage. They were friendly, patient, and willing to explain things as well as work with my through my questions. I would strongly consider using Rebel Rate to obtain your home mortgage or refinance.
Elijah O. · Google review
Reviews from Rebel Rate Mortgage's Google Business Profile. Individual results vary. Read all 37 reviews on this site.
Ready to see what fits your monthly budget?
Search Arizona homes with each home's property taxes, HOA dues, and insurance built into the estimated payment. We never sell your information or pass it to other lenders or marketers. Only Rebel Rate Mortgage, Inc. contacts you.
Create your free account to see all homes for sale that fit the monthly payment you're comfortable with, each with its actual property taxes, HOA dues, estimated homeowners insurance, and mortgage insurance when it applies, plus its own estimated closing costs and APR disclosure.
Opens a third-party home search site. Payments shown there are estimates to help you search, not a loan offer or rate quote. Your actual payment depends on price, down payment, credit, taxes, insurance, HOA, and loan program.
Prefer to talk it through? Pam Messina, NMLS #245626
Call office 602-740-9664Call Pam 602-460-4879Text PamEmail Pam
More Arizona home buyer questions · Calculators · Homes by monthly budget · All Arizona cities
Sources
- Arizona Revised Statutes §45-576 (certificates of assured water supply in active management areas; 100-year requirement) (retrieved October 27, 2026)
- Arizona Revised Statutes §45-411 (initial active management areas: Phoenix, Pinal, Prescott, Tucson) (retrieved October 27, 2026)
- Arizona Revised Statutes §45-108 (adequate water supply evaluation outside active management areas) (retrieved October 27, 2026)
- Arizona Revised Statutes §32-2181 (subdivision public report; display of an inadequate water report) (retrieved October 27, 2026)
- Arizona Revised Statutes §32-2101 (definitions: a subdivision is six or more lots) (retrieved October 27, 2026)
Frequently asked questions
What is Arizona's 100-year water rule?
Inside active management areas, new subdivisions need a certificate of assured water supply, or service from a provider designated as having one, meaning water continuously available for at least 100 years (A.R.S. §45-576).
Which areas are active management areas?
A.R.S. §45-411 set up four initial ones: Phoenix, Tucson, Prescott and Pinal. Check Arizona Department of Water Resources maps for current boundaries.
Does the rule apply to homes already built?
The certificate requirement applies when subdivided lots are offered for sale. For a resale home, check who provides its water and whether that provider is designated.
What happens outside active management areas?
Developers must have the water supply evaluated (A.R.S. §45-108). In many places an inadequate finding must be disclosed in promotional material and contracts rather than stopping sales (A.R.S. §32-2181).
Why does the six-lot rule matter?
Arizona defines a subdivision as six or more lots (A.R.S. §32-2101). Land split into fewer lots may not go through the subdivision water review, so ask about wells and water providers.
Where can I check a home's water provider?
Look at a recent water bill or ask the seller, then confirm the provider's designation with the Arizona Department of Water Resources.