Since the 1930s, Randolph's drinking water has been treated at the Randolph/Holbrook plant on Pond Street, on the Randolph side of Great Pond. That plant no longer produces water. As of July 21, 2026, all of Randolph's water has come from the Tri-Town Regional Water Treatment Plant. The new plant sits on the Braintree shore of the same pond, next to the old Braintree plant near the end of King Hill Road.
The pond is the same one Randolph has always drawn from. What changed is where the water is treated, who runs the plant, and where to look for test results. The switch happened over about two weeks in July, and the ribbon-cutting was still being discussed in September.
How the Switch Happened in July
The changeover moved faster than the official notice predicted. Here is the sequence, drawn from the Tri-Town Water District, the Town of Randolph, and Town Council minutes:
- Before July 6, 2026: The Randolph/Holbrook Joint Water Board announced that the new plant was finished and that the Massachusetts Department of Environmental Protection had approved it to start operating.
- July 6: Water from the new plant began blending gradually with water from the old plant. Operators monitored and adjusted flows across the distribution system, and the notice said the transition would take about a month.
- July 21: Randolph's supply reached 100% Tri-Town water, about two weeks after blending began.
- July 29: The town collected a finished-water PFAS sample from the new supply, the most recent one on its posted update. The lab report is dated August 12.
- August 24: At the Town Council meeting, Town Manager Howard said the new plant was "completely up and running" and that a grand reopening would be announced soon.
The startup notice told customers they might see temporary changes in water pressure, taste or odor, and minor discoloration while the system came online. It also said all water would keep meeting state and federal drinking water standards and would be tested regularly throughout. It did not issue a boil-water or do-not-drink order. The contact listed for Randolph customers was the Department of Public Works at 781-961-0940 or [email protected].
Why the Plant Is in Braintree
The arrangement goes back to 1885. That year, Chapter 217 split the waters of Great Pond, which sits in both Braintree and Randolph, among Braintree, Randolph and Holbrook. It also set up a three-member board of commissioners, one from each town. That board became the Tri-Town Water Commissioners, responsible for the Great Pond watershed, two dams, and a pump station at Richardi Reservoir.
For most of the next century, each side of the pond ran its own system. Braintree had an intake and later a treatment plant at the end of King Hill Road. Holbrook and Randolph shared an intake on the Randolph side and, from the 1930s, the treatment plant on Pond Street.
The three towns began talking about one shared replacement plant in the early 2000s. In 2019, new state legislation created the Tri-Town Water District to build it. The district's job is to supply wholesale water to Braintree, Holbrook and Randolph. Construction started in November 2022.
So the water reaching a Randolph kitchen now passes through two layers of public bodies. The Tri-Town Water District treats it and sells it wholesale. The Randolph/Holbrook Joint Water Board and the Randolph DPW handle the local side, including the startup notice and the test results.
What Happens to the Water Inside the Plant
The old Pond Street plant was replaced partly because of PFAS, the group of long-lasting chemical compounds Massachusetts now regulates in drinking water. The startup notice says the new plant was designed to remove PFAS and to meet both current and future drinking water standards.
According to the plant's contractor, the water goes through these stages:
| Stage | What the design calls for |
|---|---|
| Chemical pretreatment | Potassium permanganate and potassium hydroxide are added |
| Coagulation | Coagulants and polymer are added |
| Flocculation | Particles clump together so they can be removed |
| Dissolved-air flotation | Particles are floated off |
| Granular activated carbon filters | Remaining particles and PFAS are filtered out |
The carbon filters at the end are the main PFAS step. The project also included redundant transmission mains laid under Great Pond. The district has posted flyover video of that work, credited to Walsh Group Construction.
What the Posted PFAS Test Shows, and What It Doesn't
The most recent finished-water sample on Randolph's PFAS update was collected after the supply reached 100% Tri-Town water. It was collected July 29, 2026, and reported August 12. It lists PFAS6 as non-detect. It also lists PFHxS, PFNA, PFHpA and PFDA individually as non-detect. The town defines non-detect as meaning the compounds "were not detected at or above the laboratory's applicable analytical limits."
The state benchmark comes from MassDEP. Its PFAS6 maximum contaminant level is 20 parts per trillion, or nanograms per liter, for the combined total of six PFAS compounds. At the August 24 meeting, Councilor Gordon said the PFAS readings were below the limit.
The one-page sheet gives no numbers and no lab reporting limits. It confirms that nothing was detected at or above the lab's limits in that sample, but it does not show how far below 20 ppt the water is. The town has said it will keep posting PFAS results on the DPW section of its website. That page is now the place to check how the new plant performs over time.
So far, the town and district have published nothing on how the new water compares with the old in hardness, disinfectant, or taste once the transition ended. The only published guidance on those effects is the startup notice's warning that they would be temporary.
The Old Plant, the Money, and What's Still Pending
The 1930s Pond Street plant is now offline, and its cleanup is starting to come up at public meetings. In his August 24 report, Town Manager Howard said the money Randolph has received from the PFAS settlement is going into an account to help pay for cleaning up the old plant. The minutes do not give a scope or schedule for that work.
The new plant's cost is shared by three towns. A July 2024 Tri-Town status report put treatment-plant construction at $97,918,434 and total project costs at $122,372,534.70. As of September 2026, the district says about 95% of the total allocated budget has been spent. The 2024 figures are a budget, not a final audited cost.
The plant has been supplying water since July, and a formal opening is still in the planning stage. The agenda for the joint September 15, 2026 meeting of the Tri-Town Board of Water Commissioners and the Randolph Holbrook Joint Water Board, held at Chapin Hall in Randolph Town Hall, included "Discussion of Ribbon Cutting." That notice set no ceremony date. It listed the next meeting as October 13, 2026. The sources gathered for this post do not include a reopening date.
Some related street work is also on the town's list. At the August 24 meeting, Councilor Clerger said Hollis Street is on the list to be paved after its pipe replacement. The minutes give no paving date and do not say what kind of pipe was replaced, so that project can't be tied to the plant itself.
Questions about pressure, discoloration, or a specific address still go to the Randolph DPW, the same office as before the switch. Plant-level news, including the ribbon-cutting, comes from the Tri-Town Water District.
Buyers often ask about a home's water source and treatment, and in Randolph that answer changed this summer. At RockHome Real Estate, we follow local infrastructure changes like this one because they come up during sales. If you're curious what your Randolph home is worth now, get an instant home valuation and we'll go over it with you.
