Stand in line at the Water Mill post office on a weekday morning and you're standing inside more than a mail counter. You're inside Water Mill Square, one of exactly two commercial properties that make up nearly the entire retail center of the hamlet. Most people picking up a package or grabbing a coffee next door at Hampton Kitchen have no reason to think about who owns the building around them. This summer, a lot of them probably do.
In May, Water Mill Square at 670 Montauk Highway and The Mill at 760 Montauk Highway sold together for $39 million, a record for a Hamptons retail transaction according to the Compass brokers who arranged the deal. The two properties aren't adjacent. They aren't even the same size. But between them they hold about 84 percent of Water Mill's gross leasing area, meaning one sale just reset the ownership of nearly the entire commercial footprint of the hamlet in a single transaction.
One Deal, Most of the Map
That 84 percent figure is the part worth sitting with. Southampton's business district runs along Main Street and Jobs Lane, split among dozens of independent landlords who lease, sell, and renovate on their own timelines. Bridgehampton's restaurant strip along the turnpike works the same way. Water Mill never built that kind of fabric. Its commercial center has always sat mostly in two buildings, which is part of why the hamlet has functioned more as a pass-through between Southampton and Bridgehampton than as a destination in its own right.
That concentration is exactly what made this sale possible, and exactly what makes it matter more than a typical property transfer. When ownership of two unrelated buildings changes at once, and those two buildings account for nearly all the leasable retail space in town, the character of Water Mill's downtown effectively becomes one company's decision.
New Owners With a Different Playbook
The buyer is a joint venture between Runyon Group, led by Joseph Miller and David Fishbein, and River Oaks Properties, led by Adam Frank. Runyon is a Los Angeles firm with a track record of identifying retail concepts before they scale. Its founders have talent-spotted brands including Aesop, Blue Bottle, and Le Labo, built the Platform retail development in Culver City, and bought and later sold The Post Montecito, a comparable project in one of Santa Barbara County's highest-end suburbs. The firm says it does not flip properties. It still owns every retail project it has developed over the past two decades and leases to independent tenants rather than national chains.
The sellers were Vault Development Partners' Robert Zecher, who bought The Mill for $13.1 million in 2023, and longtime Water Mill Square owner Ben Rinzler, who had held that property since at least 2008. The two teamed up to sell both buildings as a package. Hal Zwick and Jeffrey Sztorc of the Hamptons Commercial Real Estate Team at Compass arranged the sale, the same brokers who had helped Vault acquire The Mill in 2023.
Miller has been direct about what he wants the property to feel like once the work is done:
"I want this to be a place that I can bring my kids and grab a bite to eat and let them run around that central space without worrying they could trip and literally fall into the highway."
What Changes This Summer, and What Doesn't
Nothing structural is happening yet, and nothing will this season. Miller said as much shortly after the deal closed: "This summer will feel mostly like last summer. We just closed, and we're just trying to run the buildings well and make sure current tenants are successful." The current tenant roster stays in place for now, including Aplina Bakery, Hampton Kitchen, and No. 1 Chinese at Water Mill Square, and Provisions Natural Food Market, Tight Medical Spa, Water Mill Wine & Spirits, and Hamptons Float at The Mill.
What's already in motion is smaller in scope than a redevelopment, but larger than routine upkeep:
- No new square footage is planned at either property.
- The 19 current storefronts across both plazas could grow to 22 if larger spaces, including the former Blockbuster and SoulCycle footprints at The Mill, get split into smaller shops.
- The one-acre green at the center of The Mill is being reworked with Mattituck-based designer Stacy Paetzel, with the goal of creating a buffer between the shopping center and the traffic on Montauk Highway.
- Runyon says it is working with the Water Mill Citizen Advisory Committee and Southampton Town on the plan before filing anything formal.
Southampton Town's Planning Board is watching closely, even for changes this modest. When Runyon's principals first previewed the plan last October, board member Jacqui Lofaro offered a pointed reminder of how these projects tend to unfold: "We've seen people come in saying they're going to repaint, and the next thing you know a whole wing of the building is gone." That caution is worth remembering heading into next year. A cosmetic refresh and a reconfigured storefront count both require the kind of municipal review that moves at its own pace, regardless of how confident the buyer sounds.
The Rest of the Hamlet Runs on Its Own Clock
Two buildings own most of Water Mill's commercial square footage, but they don't own the rest of what makes the hamlet what it is, and that distinction matters this summer more than usual.
The Watermill Center held its annual summer festival on July 25, presented by Van Cleef & Arpels and built around founder Robert Wilson's decades of work, with contributions this year from Laurie Anderson, Isabelle Huppert, and a roster of international artists. That event happens every summer on its own calendar, tied to an institution that predates either shopping plaza's current ownership and has nothing to do with who holds the deed on Montauk Highway.
The Water Mill Museum, housed in a working grist mill that dates back roughly 250 years, keeps its own hours through the season, showing exhibits on the hamlet's agricultural and maritime history in a building that has outlasted every retail tenant that's ever leased space nearby. A few minutes down Mecox Road, the Milk Pail extended its hours to include Wednesdays once July 4th passed, part of a farm and orchard the Halsey family has worked in the Mecox section of Water Mill since the 1640s. None of that depends on a Planning Board vote.
Even the hamlet's most recent change of use took its own long road through Town Hall. Hampton Premium Green, a cannabis dispensary that opened January 31 in a restored 1780 farmhouse at 978 Montauk Highway, previously home to 1780 House Antiques, took owners Ashley and Albert Capraro nearly three years to get through Southampton Town's site plan and permitting process before they could open the doors. Different building, different business, same lesson: in Water Mill, even a modest change to an existing structure moves through a deliberate, sometimes slow, town process no matter who's asking.
What To Watch For
The next real signal will come from the Planning Board itself, whenever it takes up Runyon's formal request to subdivide storefronts and rework the central green. Zwick has said Runyon plans to announce its broader strategy for the hamlet, though no date has been set as of this writing. Until then, the most visible sign of change will likely be the grounds work at The Mill rather than any shift in who's behind the counter.
Next time you're in line at the post office, or grabbing a sandwich at Hampton Kitchen, you're standing inside a decision that one ownership group is still making. That's not true anywhere else in the Hamptons quite the way it is in Water Mill, and it's worth knowing before the next season, when the changes now on paper start showing up on the ground.
For residents and second-home owners who want a closer read on how shifts like this ripple into Water Mill's residential market, Heskell Advisors tracks the hamlet's built environment as part of its broader work across the Bridgehampton to Wainscott corridor. Schedule a confidential market consultation to talk through what a changing downtown might mean for your own corner of Water Mill.
