On September 16, 2026, Monroeville, Ohio — a village of about 1,300 people — energized a 6 MW floating array of 9,222 modules on 12 acres of its own reservoir, described by the developer as among the five largest floating solar systems in the United States (American Public Power Association). A month earlier, the City of Lima switched on 3,120 panels across four acres of Twin Lakes, the reservoir feeding a plant that treats nearly 14 million gallons a day (WOWO). Municipal water surfaces are becoming one of the more active segments in US floating solar, and they are also the hardest to permit.
If you are an EPC looking at a water authority's reservoir, or a utilities director wondering whether the pond behind your treatment plant is a candidate, the technical questions are the easy part. The approval path is what kills these projects — and it is a completely different path from the one you follow on a stormwater or irrigation pond.
A drinking water reservoir is its own regulatory category
Most of the floating solar work happening in the US today sits on water nobody drinks: retention and stormwater ponds, process ponds, irrigation reservoirs, wastewater lagoons. On those, your approvals are mostly local — building, electrical, interconnection — plus whatever the state says about the water body itself.
Put the same array on a public water supply and you add an entire second regulator: the agency that holds primacy for the Safe Drinking Water Act in that state. That agency is not evaluating your array as a solar project. It is evaluating whether your array degrades the source water or compromises the treatment credits the utility already relies on. Those are different questions, and the people asking them have no obligation to care about your interconnection queue position.
Who actually has to say yes
The state primacy agency
The EPA delegates drinking water enforcement to states and tribes that meet its requirements, and those primacy agencies are the ones that conduct sanitary surveys — a formal review of a water system's ability to deliver safe water, covering source, treatment, distribution, storage, pumps, monitoring, management and operator compliance. Community water systems get one every three years; non-community systems every five. The requirements sit in 40 CFR Parts 142.14–142.16 and 141.401/141.723.
The "source" element of that survey is where a floating array lands. Anything you put on or anchor into the reservoir becomes a permanent feature the surveyor evaluates for contamination risk. Plan for your array to be documented in the utility's next survey, and plan for the utility to want that conversation with its regulator before it signs a contract, not after.
The state's own rules — which vary enormously
There is no national floating-solar-on-drinking-water rule. Two examples at opposite ends:
Massachusetts is restrictive. MassDEP's guidance indicates that only emergency reservoirs may be considered for these projects, and identifies three separate approvals that may apply: a New Product Review under 310 CMR 22.04(8) for equipment contacting drinking water, a construction approval under 310 CMR 22.04(4) for substantial modification of a public water system, and a land use change approval under 310 CMR 22.24. MassDEP also warns that an array could affect a supplier's ability to maintain its filtration waiver or disinfection log credits — a compliance consequence far more expensive than the array (MassDEP Q&A).
New Jersey got to yes, slowly. The Board of Public Utilities approved a roughly 10 MW, ~20-acre project on the Wanaque Reservoir in March 2026 through its Competitive Solar Incentive program, after the same project was rejected in 2024, with NJDEP oversight attached because the site sits in the Highlands (Shore News Network). Two years between rejection and approval is a realistic planning horizon for a large reservoir, not a worst case.
A federal owner, if there is one
Plenty of municipal water is stored behind federal dams. NREL's AquaPV work on federally controlled reservoirs identifies three separate federal regimes that can govern a floating array: FERC-licensed projects, Bureau of Reclamation reservoirs and US Army Corps of Engineers reservoirs, each with its own authorizations on top of state and local review (NREL / OSTI). Establish who holds title and who holds the license before you spend money on layout.
The materials question you will be asked
Expect to be asked what the floats are made of and what leaches out of them. Massachusetts spells out the standard of proof: results of testing by a nationally recognized independent testing organization showing the product is suitable for a surface water used as a drinking water source. The reference point for that kind of testing is NSF/ANSI/CAN 61, the standard covering materials in contact with drinking water.
Ask any supplier — us included — for the actual test documentation on the specific float and hardware you intend to install, in writing, before you put a reservoir project in front of a regulator. A datasheet claim is not a test report. If a supplier cannot produce one, that is your answer about whether the project is a drinking water project or a stormwater project. Our components page describes what is in a Gen3 structure kit; the documentation question is one to put to us directly through contact.
What the approval path does not exempt you from
A drinking water approval is additive, not substitutive. Even with the primacy agency satisfied, you still need:
- Local building and electrical permits, every time.
- Utility interconnection review and approval.
- Any state or regional water-body authorization that would apply anyway.
- Site-specific environmental review — the New Jersey project drew habitat conditions; Lima's involved a federal environmental review tied to its grant funding.
Nothing about floating an array removes the local permit obligations. Our page on permitting explains the post-Sackett framing for private isolated ponds — and a public water supply reservoir is close to the opposite case. Jurisdiction is site- and state-specific, and on drinking water you should assume more review, not less.
The numbers that hold up
Two 2026 projects give a useful as-built density check:
| Project | Capacity | Water covered | Density |
|---|---|---|---|
| Monroeville, OH (source) | 6 MW, 9,222 modules | 12 acres | ~87 sq ft/kW |
| Lima, OH (source) | 2 MW, 3,120 panels | 4 acres | ~87 sq ft/kW |
Both land at roughly 87 square feet of water per kilowatt installed — about 500 kW per acre of covered surface. Use 80–90 sq ft/kW for early feasibility and you will not embarrass yourself in a council meeting. For how the structure itself goes together, see how it works; for structure-kit pricing, see floating solar racking cost. Kit prices cover the floating structure only — modules, inverters and wiring are purchased separately.
On economics, Lima projects roughly $200,000 of electricity savings in year one and close to $10 million over the system's life, against a $2.4 million Department of Energy grant and nearly $900,000 in direct-pay tax credits (WOWO). Note how much of that stack is public money and elective-pay credits available to a municipal owner. A private offtaker modeling the same site should not copy those numbers.
Bottom line
Municipal reservoirs are real floating solar sites — two Ohio towns built on them this year, one of them a drinking water source — but on a public water supply you have a two-regulator project, not a one-regulator project. Before anything else, find out which agency holds Safe Drinking Water Act primacy in your state and whether it has written guidance on floating arrays; find out whether a federal agency owns or licenses the reservoir; and get independent test documentation for every component that touches the water. Then do the layout. Running those three checks takes a week and tells you whether you have a two-year project or no project.
If you are an installer or EPC who wants to quote one of these, our dealer page explains how we work with the channel, and the glossary covers the terms that come up in a water authority meeting.
This article is general information, not tax or legal advice. Drinking water, environmental and permitting requirements are site- and state-specific — confirm your obligations with your state primacy agency and qualified counsel before committing to a project.
Sources: US EPA — Sanitary Surveys · MassDEP — Q&A, Floating Solar on Public Water Supply Reservoirs · American Public Power Association — 6 MW floating array energized in Monroeville, Ohio · WOWO — Lima flips switch on 2 MW floating array at Twin Lakes · Shore News Network — New Jersey approves 20-acre Wanaque Reservoir project · NREL / OSTI — AquaPV: Regulatory and Environmental Considerations for FPV on Federally Controlled Reservoirs · NSF — NSF/ANSI/CAN 61 Testing and Certification
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