Two Parcels, One Well: What a Shared-Well Agreement Has to Say

A forty-acre parcel near Kansas Settlement gets split. The well is on the north half. The buyer of the south half is told, in good faith, that the well is shared. Nothing is written down beyond a line in the listing.

Three years later the pump fails, the north owner wants to split the repair bill, and the south owner points out that the well is not on their land. Neither has a document that settles it.

That is why the recorded agreement matters. There is no regulator and no default rulebook. Whatever the two owners wrote down is the entire set of rules, and if they wrote nothing down, the rules are whatever a judge later decides they should have been.

What a shared well is, in the state's terms

ADWR treats a well serving up to 14 service connections, or up to 24 residents, as a shared well. At 15 connections or 25 residents served year-round it becomes a community water system under ADEQ's public-water rules.

Nearly all of these wells are exempt domestic wells, which under A.R.S. § 45-454 means a pump of no more than 35 gallons per minute for non-irrigation use. "Domestic" includes watering less than two acres of plants and stock watering. It does not include irrigating a field.

What the Willcox AMA changed, and what it did not

The Willcox groundwater basin became an active management area with an official designation date of 8 January 2025, after a Director's decision on 19 December 2024. The basin is defined as the surface watershed draining to the Willcox Playa in the northern Sulphur Springs Valley, plus the upper Leslie Creek and Rucker Canyon watersheds east of the Swisshelms. That is a watershed line, not a town line. Willcox and Kansas Settlement are plainly inside it; whether a given parcel around Pearce, Sunsites or Dragoon is inside depends on where the line falls, so check the ADWR boundary map for your own parcel rather than assuming.

For a shared domestic well the consequences are narrower than the headlines suggested:

• Exempt wells are still exempt from metering and annual reporting. Non-exempt wells had to be metered by 31 March 2025 and report annually.
• A new exempt well still needs a notice of intent to drill, a licensed driller, construction standards and a completion report. On a parcel of five acres or less it also needs a site plan showing 100 feet of separation from any septic tank or sewer line, and county health approval.
• Commercial withdrawals from an exempt well are capped at 10 acre-feet a year.
• Inside an AMA, § 45-454 allows only one exempt well to serve the same non-irrigation use at the same location, with a narrow second-well exception.

None of that prevents two parcels from sharing a well. It does mean the common fix for a failed arrangement, "we will just drill our own", is subject to the one-exempt-well rule, and is worth checking with ADWR before you count on it.

What the agreement has to cover

The University of Arizona Cooperative Extension guide on shared wells (AZ1810) is the closest thing Arizona has to a checklist. It says the agreement must be signed, notarised and recorded so that it becomes part of each title record, that there is no standard format, that it should describe the easements for water-line access to each home, and that drafting one for a fee is practising law, so an attorney should be involved. Read alongside what lenders ask for, a usable agreement answers at least these questions:

Recording is cheap: a flat $30 per document at the Cochise County Recorder under A.R.S. § 11-475, with electronic recording available through the providers the Bisbee office lists.

What a lender will ask for

If either parcel will ever be sold with a mortgage, the agreement is being written for the lender as much as for the neighbours. HUD's reference guidance for FHA loans says a shared well may serve no more than four living units or properties, that each dwelling's service line needs a valve where it leaves the well, and that there must be a shared-well agreement binding on the signing parties and their successors in title. That page is archived; confirm the current wording in HUD Handbook 4000.1 before relying on it.

Fannie Mae's Selling Guide requires that a property using an off-site private well have the right to use it, supported by "an adequate, legally binding agreement for access and maintenance". The Extension guide adds that above four homes, FHA and VA lenders prefer the well registered to a co-op or non-profit LLC with the power and a bank account in its name. A verbal arrangement fails every one of those tests. So does an unrecorded letter.

Water quality is your problem too

Arizona sets no water-quality standard for a non-public shared well. AZ1810 recommends testing for coliform twice a year, for nitrate, nitrite, dissolved solids and pH annually, and for arsenic and uranium at least once with retesting every two to three years. Who pays for that belongs in the agreement too.

If you are weighing a share arrangement against your own well or hauled water, the numbers are in our hauled water versus drilling post, and shared wells are one of the things a parcel split tends to create without anyone planning for it. Trenching a water line along an easement is ordinary work; tell us the parcel and the job and a licensed local contractor will call you to quote it.

What we could not confirm

• We are not attorneys and this is not legal advice. A well-share agreement is a contract and an easement. Have it drafted or reviewed by an Arizona real estate attorney.
• We could not confirm how ADWR applies the one-exempt-well-per-location rule in § 45-454 to two parcels drawing from one well, or what happens if the arrangement ends and the second parcel wants its own well. Ask ADWR.
• The HUD shared-well guidance we read is an archived page. We did not locate the equivalent section of the current Handbook 4000.1.
• Statutory text is from the Arizona Revised Statutes as published online. Check the current text before relying on it.

The short version

No Arizona agency regulates or enforces a well-sharing agreement, so the recorded document is the only rulebook. Record one that states who owns the equipment, where the well-site and water-line easements run, how power, repairs and replacement are split, who can authorise an emergency repair, what the water may be used for, that it binds successors, and how disputes end. Recording costs $30. Inside the Willcox AMA an exempt domestic well is still unmetered, but a second well is subject to the one-well-per-use rule. Lenders want the agreement recorded, binding on successors, with a valve on each service line and no more than four homes on the well.